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A week is a unit of time equal to seven days. It is the standard time period used for short cycles of days in most parts of the world. The days are often used to indicate common work days and rest days, as well as days of worship. Weeks are often mapped against yearly calendars. There are just over 52 weeks in a year. The term "week" may also be used to refer to a sub-section of the week, such as the workweek and weekend.

Ancient cultures had different "week" lengths, including ten days in Egypt and an eight-day week for Etruscans. The Etruscan week was adopted by the ancient Romans, but they later moved to a seven-day week, which had spread across Western Asia and the Eastern Mediterranean due to the influence of the Christian seven-day week, which is rooted in the Jewish seven-day week. In AD 321, Emperor Constantine the Great officially decreed a seven-day week in the Roman Empire, including making Sunday a public holiday.[1][2] This later spread across Europe, then the rest of the world.

World map showing the first day of the week used in different countries according to the Common Locale Data Repository[3]
  Monday
  Friday (Maldives only)
  Saturday
  Sunday

In English, the names of the days of the week are Monday, Tuesday, Wednesday, Thursday, Friday, Saturday and Sunday. In many languages, including English, the days of the week are named after gods or classical planets. Saturday has kept its Roman name, while the other six days use Germanic equivalents. Such a week may be called a planetary week (i.e., a classical planetary week).[4] Certain weeks within a year may be designated for a particular purpose, such as Golden Week in China and Japan. More informally, certain groups may advocate awareness weeks, such as National Family Week in Canada, which are designed to draw attention to a certain subject or cause.

Cultures vary in which days of the week are designated the first and the last, though virtually all have Saturday, Sunday or Monday as the first day. The Geneva-based ISO standards organization uses Monday as the first day of the week in its ISO week date system through the international ISO 8601 standard.[a] Most of Europe and China consider Monday the first day of the (work) week, while North America, South Asia, and many Catholic and Protestant countries, consider Sunday the first day of the week. It is also the first day of the week in almost all of the Arabic speaking countries.[contradictory] This is culturally and historically the case since in Arabic Sunday is referred to as "Yaom Al'Ahad" which literally means "The first day".[5][6] Other regions are mixed, but typically observe either Sunday or Monday as the first day.[7]

The three Abrahamic religions observe different days of the week as their holy day. Jews observe their Sabbath (Shabbat) on Saturday, the seventh day, from sundown Friday to sundown Saturday, in honor of God's creation of the world in six days and then resting on the seventh.[8] Most Christians observe Sunday (the Lord's Day), the first day of the week in traditional Christian calendars, in honor of the resurrection of Jesus. [9] Muslims observe their "day of congregation", known as yaum al-jum`ah, on Friday because it was described as a sacred day of congregational worship in the Quran.[10]

Name

[edit]

The English word week comes from the Old English wice, ultimately from a Common Germanic *wikōn-, from a root *wik- "turn, move, change". The Germanic word probably had a wider meaning prior to the adoption of the Roman calendar, perhaps "succession series", as suggested by Gothic wikō translating taxis "order" in Luke 1:8.

The seven-day week is named in many languages by a word derived from "seven". The archaism sennight ("seven-night") preserves the old Germanic practice of reckoning time by nights, as in the more common fortnight ("fourteen-night").[11] Hebdomad and hebdomadal week both derive from the Greek hebdomás (ἑβδομάς, "a seven"). Septimana is cognate with the Romance terms derived from Latin septimana ("seven mornings").

Definition and duration

[edit]

A week is defined as an interval of exactly seven days,[b] so that, except when passing through daylight saving time transitions or leap seconds,

1 week = 7 days = 168 hours = 10,080 minutes = 604,800 seconds.

With respect to the Gregorian calendar:

  • 1 Gregorian calendar year = 52 weeks + 1 day (2 days in a leap year)
  • 1 week = 1600⁄6957 ≈ 22.9984% of an average Gregorian month

In a Gregorian mean year, there are 365.2425 days, and thus exactly 52+71⁄400 or 52.1775 weeks (unlike the Julian year of 365.25 days or 52+5⁄28 ≈ 52.1786 weeks). There are exactly 20,871 weeks in 400 Gregorian years, so 31 October 1625 was a Friday just as was 31 October 2025.

Relative to the path of the Moon, a week is 23.659% of an average lunation or 94.637% of an average quarter lunation.

Historically, the system of dominical letters (letters A to G identifying the weekday of the first day of a given year) has been used to facilitate calculation of the day of week. The day of the week can be easily calculated given a date's Julian day number (JD, i.e. the integer value at noon UT): Adding one to the remainder after dividing the Julian day number by seven (JD modulo 7 + 1) yields that date's ISO 8601 day of the week. For example, the Julian day number of 31 October 2025 is 2460980. Calculating 2460980 mod 7 + 1 yields 5, corresponding to Friday.[12] In 1973, John Conway devised the Doomsday rule for mental calculation of the weekday of any date in any year.

Days of the week

[edit]
Main article: Names of the days of the week
An Italian cameo bracelet representing the days of the week by their eponymous deities (mid-19th century, Walters Art Museum)
Schematic comparison of the ordering of the classical planets (arranged in a circle) and the sequence of days in the week (forming a {7/3} heptagram within the circle).

The days of the week were named for the seven classical planets, which included the Sun and Moon. This naming system persisted alongside an "ecclesiastical" tradition of numbering the days in ecclesiastical Latin beginning with Dominica (the Lord's Day) as the first day. The Greco-Roman gods associated with the classical planets were rendered in their interpretatio germanica at some point during the late Roman Empire, yielding the Germanic tradition of names based on indigenous deities.

The ordering of the weekday names is not the classical order of the planets (by distance in the planetary spheres model, which is Moon, Mercury, Venus, Sun, Mars, Jupiter, Saturn); nor, equivalently, by their apparent speed of movement in the night sky. Instead, the planetary hours systems resulted in succeeding days being named for planets that are three places apart in their traditional listing. This characteristic was apparently discussed in Plutarch in a treatise written in c. 100 CE, which is reported to have addressed the question of Why are the days named after the planets reckoned in a different order from the actual order? (the text of Plutarch's treatise has been lost).[13] Dio Cassius (early 3rd century) gives two explanations in a section of his Historia Romana after mentioning the Jewish practice of sanctifying the day called the day of Kronos (Saturday).[14]

Sunday Monday Tuesday Wednesday Thursday Friday Saturday
Planet Sun Moon Mars Mercury Jupiter Venus Saturn
Greco-Roman deity Helios-Sol Selene-Luna Ares-Mars Hermes-Mercury Zeus-Jupiter Aphrodite-Venus Cronus-Saturn
Greek:[14] ἡμέρα Ἡλίου ἡμέρα Σελήνης ἡμέρα Ἄρεως ἡμέρα Ἑρμοῦ ἡμέρα Διός ἡμέρα Ἀφροδίτης ἡμέρα Κρόνου
Latin: dies Sōlis dies Lūnae dies Martis dies Mercuriī dies Iovis dies Veneris dies Saturnī
interpretatio germanica Sun Moon Tiwaz Wodanaz Þunraz Frige —
Old English sunnandæg mōnandæg tiwesdæg wōdnesdæg þunresdæg frīgedæg sæterndæg
Indian Navagraha Suryavāra/

Ravivāra/Bhānuvāsara/Ādityavāra

Chandravāra/

Somavāra/

Induvāsara

Mangalavāra/ Bhaumavāsara Budhavāra/

Saumyavāsara

Guruvāra/Bṛhaspativāsara Shukravāra/ Bhṛguvāsara Shanivāra/

Sthiravāsara

An ecclesiastical, non-astrological, system of numbering the days of the week was adopted in Late Antiquity. This model also seems to have influenced (presumably via Gothic) the designation of Wednesday as "mid-week" in Old High German (mittawehha) and Old Church Slavonic (срѣда, srěda, literally, middle day). Old Church Slavonic may have also modeled the name of Monday, понєдѣльникъ (literally, the day after Sunday), after the Latin feria Secunda.[15]

The ecclesiastical system became prevalent in Eastern Christianity, but in the Latin West it remains extant only in modern Icelandic, Galician, and Portuguese.[16]

"First Day" or
"Lord's Day"
(Sunday)		 "Second Day"
(Monday)		 "Third Day"
(Tuesday)		 "Fourth Day"
(Wednesday)		 "Fifth Day"
(Thursday)		 "Sixth Day"
(Friday)		 "Seventh Day" or
"Sabbath"
(Saturday)
Greek Κυριακὴ ἡμέρα
/kiriaki iméra/ 		Δευτέρα ἡμέρα
/devtéra iméra/ 		Τρίτη ἡμέρα
/tríti iméra/ 		Τετάρτη ἡμέρα
/tetárti iméra/ 		Πέμπτη ἡμέρα
/pémpti iméra/ 		Παρασκευὴ ἡμέρα
/paraskevi iméra/[17] 		Σάββατον
/sáb:aton/
Latin [dies] dominica;
rarely feria prima, feria dominica 		feria secunda feria tertia feria quarta;
rarely media septimana 		feria quinta feria sexta Sabbatum; dies sabbatinus, dies Sabbati;
rarely feria septima, feria Sabbati
Hebrew Hebrew: יום ראשון, romanized: Yom rishon, lit. 'first day' Hebrew: יום שני, romanized: Yom sheni, lit. 'second day' Hebrew: יום שלישי, romanized: Yom shlishi, lit. 'third day' Hebrew: יום רביעי, romanized: Yom revi'i, lit. 'fourth day' Hebrew: יום חמישי, romanized: Yom chamishi, lit. 'fifth day' Hebrew: יום שישי, romanized: Yom shishi, lit. 'sixth day' Hebrew: שבת, romanized: Shabbat, lit. 'Rest/cessation'

History

[edit]
Circular diagrams showing the division of the day and of the week, from a Carolingian ms. (Clm 14456 fol. 71r) of St. Emmeram Abbey. The week is divided into seven days, and each day into 24 hours, 96 puncta (quarter-hours), 240 minuta (tenths of an hour) and 960 momenta (40th parts of an hour).

Ancient Near East

[edit]

The earliest evidence of an astrological significance of a seven-day period is a decree of king Sargon of Akkad around 2300 BCE. Akkadians venerated the number seven, and the key celestial bodies visible to the naked eye numbered seven (the Sun, the Moon and the five closest planets).[18]

Gudea, the priest-king of Lagash in Sumer during the Gutian dynasty (about 2100 BCE), built a seven-room temple, which he dedicated with a seven-day festival. In the flood story of the Assyro-Babylonian Epic of Gilgamesh, the storm lasts for seven days, the dove is sent out after seven days (similarly in Genesis), and the Noah-like character of Utnapishtim leaves the ark seven days after it reaches the firm ground.[c]

Counting from the new moon, the Babylonians celebrated the 7th, 14th, 21st and 28th of the approximately 29- or 30-day lunar month as "holy days", also called "evil days" (meaning inauspicious for certain activities). On these days, officials were prohibited from various activities and common men were forbidden to "make a wish", and at least the 28th was known as a "rest day".[22] On each of them, offerings were made to a different god and goddess. Though similar, the later practice of associating days of the week with deities or planets is not due to the Babylonians.[23]

Judaism

[edit]

A continuous seven-day cycle that runs throughout history without reference to the phases of the moon was first practiced in Judaism, dated to the 6th century BCE at the latest.[24][25]

There are several hypotheses concerning the origin of the biblical seven-day cycle.

Friedrich Delitzsch and others suggested that the seven-day week being approximately a quarter of a lunation is the implicit astronomical origin of the seven-day week,[26] and indeed the Babylonian calendar used intercalary days to synchronize the last week of a month with the new moon.[27] According to this theory, the Jewish week was adopted from the Babylonians while removing the moon-dependency.

George Aaron Barton speculated that the seven-day creation account of Genesis is connected to the Babylonian creation epic, Enûma Eliš, which is recorded on seven tablets.[28]

In a frequently-quoted suggestion going back to the early 20th century,[29] the Hebrew Sabbath is compared to the Sumerian sa-bat "mid-rest", a term for the full moon. The Sumerian term has been reconstructed as rendered Sapattum or Sabattum in Babylonian, possibly present in the lost fifth tablet of the Enûma Eliš, tentatively reconstructed [according to whom?] "[Sa]bbath shalt thou then encounter, mid[month]ly".[22]

However, Niels-Erik Andreasen, Jeffrey H. Tigay, and others claim that the Biblical Sabbath is mentioned as a day of rest in some of the earliest layers of the Pentateuch dated to the 9th century BCE at the latest, centuries before the Babylonian exile of Judah. They also find the resemblance between the Biblical Sabbath and the Babylonian system to be weak. Therefore, they suggest that the seven-day week may reflect an independent Israelite tradition.[30][31][32][33] Tigay writes:

It is clear that among neighboring nations that were in position to have an influence over Israel – and in fact which did influence it in various matters – there is no precise parallel to the Israelite Sabbatical week. This leads to the conclusion that the Sabbatical week, which is as unique to Israel as the Sabbath from which it flows, is an independent Israelite creation.[32][34]

The seven-day week seems to have been adopted, at different stages, by the Persian Empire, in Hellenistic astrology, and (via Greek transmission) in Gupta India and Tang China.[d][citation needed] The Babylonian system was received by the Greeks in the 4th century BCE (notably via Eudoxus of Cnidus). Although some sources, such as the Encyclopædia Britannica,[8] state that the Babylonians named the days of the week after the five planets, the sun, and the moon, many scholars disagree. Eviatar Zerubavel says, "the establishment of a seven-day week based on the regular observance of the Sabbath is a distinctively Jewish contribution to civilization. The choice of the number 7 as the basis for the Jewish week might have had an Assyrian or Babylonian origin, yet it is crucial to remember that the ancient dwellers of Mesopotamia themselves did not have a seven-day week."[36] The astrological concept of planetary hours is an innovation of Hellenistic astrology, probably first conceived in the 2nd century BCE.[37]

The seven-day week was widely known throughout the Roman Empire by the 1st century CE,[38] along with references to the Jewish Sabbath by Roman authors such as Seneca and Ovid.[39] When the seven-day week came into use in Rome during the early imperial period, it did not immediately replace the older eight-day nundinal system.[40] The nundinal system had probably fallen out of use by the time Emperor Constantine adopted the seven-day week for official use in CE 321, making the Day of the Sun (dies Solis) a legal holiday.[41]

Achaemenid period

[edit]

The Zoroastrian calendar follows the Babylonian in relating the 7th, 14th, 21st, and 28th of the 29- or 30-day lunar month to Ahura Mazda.[42] The forerunner of all modern Zoroastrian calendars is the system used to determine dates in the Persian Empire, adopted from the Babylonian calendar by the 4th century BCE.

Frank C. Senn in his book Christian Liturgy: Catholic and Evangelical points to data suggesting evidence of an early continuous use of a seven-day week; referring to the Jews during the Babylonian captivity in the 6th century BCE,[25] after the destruction of the Temple of Solomon. While the seven-day week in Judaism is tied to Creation account in the Book of Genesis in the Hebrew Bible, it is not clear whether the Genesis narrative predates the Babylonian captivity of the Jews in the 6th century BCE. At least since the Second Temple period under Persian rule, Judaism relied on the seven-day cycle of recurring Sabbaths.[25]

Tablets[citation needed] from the Achaemenid period indicate that the lunation of 29 or 30 days basically contained three seven-day weeks, and a final week of eight or nine days inclusive, breaking the continuous seven-day cycle.[22] The Babylonians additionally celebrated the 19th as a special "evil day", the "day of anger", because it was roughly the 49th day of the (preceding) month, completing a "week of weeks", also with sacrifices and prohibitions.[22]

Difficulties with Friedrich Delitzsch's origin theory connecting Hebrew Shabbat with the Babylonian lunar cycle[43] include reconciling the differences between an unbroken week and a lunar week, and explaining the absence of texts naming the lunar week as Shabbat in any language.[44]

Hellenistic and Roman era

[edit]
Main article: Nundinae

In Jewish sources by the time of the Septuagint, the term "Sabbath" by synecdoche also came to refer to an entire seven-day week,[45] the interval between two weekly Sabbaths. Jesus's parable of the Pharisee and the Publican describes the Pharisee as fasting "twice in the week". In the account of the women finding the tomb empty, they are described as coming there "toward the one of the sabbaths"; translations substitute "week" for "sabbaths".

The ancient Romans traditionally used the eight-day nundinum but, after the Julian calendar had come into effect in 45 BCE, the seven-day week came into increasing use. For a while, the week and the nundinal cycle coexisted, but by the time the week was officially adopted by Constantine in 321 CE, the nundinal cycle had fallen out of use. The association of the days of the week with the Sun, the Moon and the five planets visible to the naked eye dates to the Roman era (2nd century).[46][25]

The continuous seven-day cycle of the days of the week can be traced back to the reign of Augustus; the first identifiable date cited complete with day of the week is 6 February 60 CE, identified as a "Sunday" (as viii idus Februarius dies solis "eighth day before the ides of February, day of the Sun") in a Pompeiian graffito. According to the (contemporary) Julian calendar, 6 February 60 was, however, a Wednesday. This is explained by the existence of two conventions of naming days of the weeks based on the planetary hours system: 6 February was a "Sunday" based on the sunset naming convention, and a "Wednesday" based on the sunrise naming convention.[47]

Islamic concept

[edit]

According to Islamic beliefs, the seven-day week concept started with the creation of the universe by Allah. Abu Huraira reported that Muhammad said: Allah, the Exalted and Glorious, created the clay on Saturday and He created the mountains on Sunday and He created the trees on Monday and He created the things entailing labour on Tuesday and created light on Wednesday and He caused the animals to spread on Thursday and created Adam after 'Asr on Friday; the last creation at the last hour of the hours of Friday, i.e., between afternoon and night.[48]

Adoption in Asia

[edit]

China and Japan

[edit]

The earliest known reference in Chinese writings to a seven-day week is attributed to Fan Ning, who lived in the late 4th century in the Jin dynasty, while diffusions from the Manichaeans are documented with the writings of the Chinese Buddhist monk Yi Jing and the Ceylonese or Central Asian Buddhist monk Bu Kong of the 7th century (Tang dynasty).

The Chinese variant of the planetary system was brought to Japan by the Japanese monk Kūkai (9th century). Surviving diaries of the Japanese statesman Fujiwara Michinaga show the seven-day system in use in Heian Period Japan as early as 1007. In Japan, the seven-day system was kept in use for astrological purposes until its promotion to a full-fledged Western-style calendrical basis during the Meiji Period (1868–1912).

India

[edit]

The seven-day week was known in India by the 6th century, referenced in the Pañcasiddhāntikā.[citation needed] Shashi (2000) mentions the Garga Samhita, which he places in the 1st century BCE or CE, as a possible earlier reference to a seven-day week in India. He concludes "the above references furnish a terminus ad quem (viz. 1st century) The terminus a quo cannot be stated with certainty".[49][50]

Christian Europe

[edit]
Further information: Holy Week and Easter Week

The seven-day weekly cycle has remained unbroken in Christendom, and hence in Western history, for almost two millennia, despite changes to the Coptic, Julian, and Gregorian calendars, demonstrated by the date of Easter Sunday having been traced back through numerous computistic tables to an Ethiopic copy of an early Alexandrian table beginning with the Easter of 311 CE.[51][52]

A tradition of divinations arranged for the days of the week on which certain feast days occur develops in the early medieval period. There are many later variants of this, including the German Bauern-Praktik and the versions of Erra Pater published in 16th- to 17th-century England, mocked in Samuel Butler's Hudibras. South and East Slavic versions are known as koliadniki (from koliada, a loan of Latin calendae), with Bulgarian copies dating from the 13th century, and Serbian versions from the 14th century.[53]

Medieval Christian traditions associated with the lucky or unlucky nature of certain days of the week survived into the modern period. This concerns primarily Friday, associated with the crucifixion of Jesus. Sunday, sometimes personified as Saint Anastasia, was itself an object of worship in Russia, a practice denounced in a sermon extant in copies going back to the 14th century.[54]

Sunday, in the ecclesiastical numbering system also counted as the feria prima or the first day of the week; yet, at the same time, figures as the "eighth day", and has occasionally been so called in Christian liturgy.[e]

Justin Martyr wrote: "the first day after the Sabbath, remaining the first of all the days, is called, however, the eighth, according to the number of all the days of the cycle, and [yet] remains the first."[55]

A period of eight days, usually (but not always, mainly because of Christmas Day) starting and ending on a Sunday, is called an octave, particularly in Roman Catholic liturgy. In German, the phrase heute in acht Tagen (literally "today in eight days") can also mean one week from today (i.e. on the same weekday). The same is true of the Italian phrase oggi otto (literally "today eight"), the French à huitaine, and the Spanish de hoy en ocho.

Numbering

[edit]
Further information: Leap week calendar

Weeks in a Gregorian calendar year can be numbered for each year. This style of numbering is often used in European and Asian countries. It is less common in the U.S. and elsewhere.

ISO week date system

[edit]

The system for numbering weeks is the ISO week date system, which is included in ISO 8601. This system dictates that each week begins on a Monday and is associated with the year that contains that week's Thursday.

Determining Week 1

[edit]

In practice week 1 (W01 in ISO notation) of any year can be determined as follows:

  • If 1 January falls on a Monday, Tuesday, Wednesday or Thursday, then the week of 1 January is Week 1. Except in the case of 1 January falling on a Monday, this Week 1 includes the last day(s) of the previous year.
  • If 1 January falls on a Friday, Saturday, or Sunday, then 1 January is considered to be part of the last week of the previous year. Week 1 will begin on the first Monday after 1 January.

Examples:

  • Week 1 of 2015 (2015W01 in ISO notation) started on Monday, 29 December 2014 and ended on Sunday, 4 January 2015, because 1 January 2015 fell on Thursday.
  • Week 1 of 2021 (2021W01 in ISO notation) started on Monday, 4 January 2021 and ended on Sunday, 10 January 2021, because 1 January 2021 fell on Friday.

Week 52 and 53

[edit]

It is also possible to determine if the last week of the previous year was Week 52 or Week 53 as follows:

  • If 1 January falls on a Friday, then it is part of Week 53 of the previous year (W53-5).
  • If 1 January falls on a Saturday,
    • then it is part of Week 53 of the previous year if that is a leap year (W53-6),
    • and part of Week 52 otherwise (W52-6), i.e. if the previous year is a common year.
  • If 1 January falls on a Sunday, then it is part of Week 52 of the previous year (W52-7).

Schematic representation of ISO week date

[edit]
Dominical letter(s) plus weekdays, dates and week numbers at the beginning and end of a year
Dominical
letter(s)1 		Days at the start of January Effect1,2 Days at the end of December1
1
Mon		 2
Tue		 3
Wed		 4
Thu		 5
Fri		 6
Sat		 7
Sun 		W01-13 01 Jan week ... 31 Dec week 1
Mon4		 2
Tue		 3
Wed		 4
Thu		 5
Fri		 6
Sat		 7
Sun
G(F) 01 02 03 04 05 06 07 01 Jan W01 ... W01 31 (30) (31)
F(E) 01 02 03 04 05 06 31 Dec W01 ... W01 30 (29) 31 (30) (31)
E(D) 01 02 03 04 05 30 Dec W01 ... W01 (W53) 29 (28) 30 (29) 31 (30) (31)
D(C) 01 02 03 04 29 Dec W01 ... W53 28 (27) 29 (28) 30 (29) 31 (30) (31)
C(B) 01 02 03 04 Jan W53 ... W52 27 (26) 28 (27) 29 (28) 30 (29) 31 (30) (31)
B(A) 01 02 03 Jan W52 (W53) ... W52 26 (25) 27 (26) 28 (27) 29 (28) 30 (29) 31 (30) (31)
A(G) 01 02 Jan W52 ... W52 (W01) 25 (31) 26 (25) 27 (26) 28 (27) 29 (28) 30 (29) 31 (30)

Notes
1. Numbers and letters in parentheses, ( ), apply to March − December in leap years.
2. Underlined numbers and letters belong to previous year or next year.
3. First date of the first week in the year.
4. First date of the last week in the year.

Other week numbering systems

[edit]

In some countries, though, the numbering system is different from the ISO standard. At least six numberings are in use:[56][57] [dubious – discuss]

System First day of week First week of year contains Can be last week of previous year Used by or in
ISO 8601 Monday 4 January 1st Thursday 4–7 days of year yes EU (exc. Portugal) and most other European countries, most of Asia and Oceania
Middle Eastern Saturday 1 January 1st Friday 1–7 days of year yes Much of the Middle East
Western traditional Sunday 1 January 1st Saturday 1–7 days of year yes Canada, United States, Iceland, Portugal, Japan, Taiwan, Thailand, Hong Kong, Macau, Israel, Egypt, South Africa, the Philippines, and most of Latin America
Broadcast Calendar Monday 1 January 1st Sunday 1–7 days of year yes Broadcast services in the United States[58]

Because the week starts on either Saturday, Sunday, or Monday in all these systems, the days in a workweek, Monday through Friday, will always have the same week number within a calendar week system. Quite often, these systems will agree on the week number for each day in a workweek:

Note that this agreement occurs only for the week number of each day in a work week, not for the day number within the week, nor the week number of the weekends.

The epi week (epidemiological week) is used to report healthcare statistics, as with COVID-19 cases:[59]

The epidemiological week begins on Sunday and ends on Saturday. The first epidemiological week of the year ends on the first Saturday of January, provided that it falls at least four or more days into the month. Therefore, the first epidemiological week may actually begin in December of the previous year.

Uses

[edit]

The semiconductor package date code is often a 4 digit date code YYWW where the first two digits YY are the last 2 digits of the calendar year and the last two digits WW are the two-digit week number.[60][61]

The tire date code mandated by the US DOT is a 4 digit date code WWYY with two digits of the week number WW followed by the last two digits of the calendar year YY.[62]

"Weeks" in other calendars

[edit]

The term "week" is sometimes expanded to refer to other time units comprising a few days. Such "weeks" of between four and ten days have been used historically in various places.[63] Intervals longer than 10 days are not usually termed "weeks" as they are closer in length to the fortnight or the month than to the seven-day week.

Pre-modern

[edit]

Calendars unrelated to the Chaldean, Hellenistic, Christian, or Jewish traditions often have time cycles between the day and the month of varying lengths, sometimes also called "weeks".

An eight-day week was used in Ancient Rome and possibly in the pre-Christian Celtic calendar. Traces of a nine-day week are found in Baltic languages and in Welsh. The ancient Chinese calendar had a ten-day week, as did the ancient Egyptian calendar (and, incidentally, the French Republican Calendar, dividing its 30-day months into thirds).

A six-day week was used in the Akan calendar and Kabiye culture in West Africa until 1981. Several cultures used a five-day week, including the Javanese calendar and the traditional cycle of market days in Korea.[citation needed] The Igbo have a "market week" of four days. Evidence of a "three-day week" has been derived from the names of the days of the week in Guipuscoan Basque.[64]

The Aztecs and Mayas used the Mesoamerican calendars. The most important of these calendars divided a ritual cycle of 260 days (known as Tonalpohualli in Nahuatl and Tzolk'in in Yucatec Maya) into 20 weeks of 13 days (known in Spanish as trecenas). They also divided the solar year into 18 periods (winal) of 20 days and five nameless days (wayebʼ), creating a 20-day month divided into four five-day weeks. The end of each five-day week was a market day.[65][66]

The Balinese Pawukon is a 210-day calendar consisting of 10 different simultaneously running weeks of 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 days, of which the weeks of 4, 8, and 9 days are interrupted to fit into the 210-day cycle.

Modern reforms

[edit]
Further information: International Fixed Calendar, Decimal calendar, French Revolutionary Calendar § Ten days of the week, and Bahá'í calendar

The International Fixed Calendar (also known as the "Eastman plan") kept a 7-day week while defining a year of 13 months with 28 days each (364 days). Every calendar date was always on the same weekday. It was the official calendar of the Eastman Kodak Company for decades.[citation needed]

A 10-day week, called a décade, was used in Revolutionary France for nine and a half years from October 1793 to April 1802.[67] The Paris Commune adopted this calendar for 18 days in 1871.

The Bahá'í calendar features a 19-day period that some classify as a month and others classify as a week.[68]

Soviet

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Further information: Soviet calendar
Soviet calendar, 1930.
Five colors of five-day work week repeat.
Soviet calendar, 1933.
Rest day of six-day work week in blue.
Days of each Gregorian month in both calendars are grouped vertically into seven-day weeks.

In the Soviet Union between 1929 and 1940, most factory and enterprise workers, but not collective farm workers, used five and six day work weeks while the country as a whole continued to use the traditional seven day week.[69][70][71]

From 1929 to 1951, five national holidays were days of rest (22 January, 1–2 May, 7–8 November). From autumn 1929 to summer 1931, the remaining 360 days of the year were subdivided into 72 five day work weeks beginning on 1 January. Workers were assigned any one of the five days as their day off, even if their spouse or friends might be assigned a different day off. Peak use of the five day work week occurred on 1 October 1930 at 72% of industrial workers. From summer 1931 until 26 June 1940, each Gregorian month was subdivided into five six day work weeks, more-or-less, beginning with the first day of each month. The sixth day of each six day work week was a uniform day of rest. On 1 July 1935 74.2% of industrial workers were on non-continuous schedules, mostly six day work weeks, while 25.8% were still on continuous schedules, mostly five day work weeks. The Gregorian calendar with its irregular month lengths and the traditional seven day week were used in the Soviet Union during its entire existence, including 1929–1940; for example, in the masthead of Pravda, the official Communist newspaper, and in both Soviet calendars displayed here. The traditional names of the seven day week continued to be used, including "Resurrection" (Воскресенье) for Sunday and "Sabbath" (Суббота) for Saturday, despite the government's official atheism.

See also

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Wikimedia Commons has media related to Week.

Notes

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References

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Further reading

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Week

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The week is a equal to seven consecutive days, functioning as the primary short-term cycle in the and most other modern calendars worldwide. This seven-day division originated in ancient around 2300 BCE, where early astronomers and astrologers associated each day with one of the seven celestial bodies visible to the —the Sun, , Mercury, Venus, , , and Saturn—establishing a recurring planetary week independent of lunar or solar phases. The structure spread through Jewish tradition, which codified a creation-based seven-day cycle with a rest, and was later institutionalized in the by Emperor Constantine's 321 CE decree recognizing the seven-day week and designating as a , facilitating its adoption across Christian, Islamic, and eventually global societies despite historical experiments with alternative lengths like the eight-day Roman nundina or twentieth-century Soviet five-day and six-day weeks. Although the cycle itself is now nearly universal, conventions for its starting day differ: the (ISO 8601) defines Monday as the first day, aligning with business practices in most countries, while Sunday initiates the week in the United States and several others influenced by observance.

Definition and Basic Characteristics

Duration and Structure

The week consists of seven consecutive days, a duration established as the international standard in most calendars worldwide. This fixed length of seven days forms a repeating cycle independent of longer astronomical periods like the solar year or , though its origins approximate a quarter of the lunar cycle (approximately 28 days divided into four seven-day segments). Structurally, the week is a simple sequence of seven solar days—each defined as one full rotation of Earth relative to the Sun—without embedded subdivisions beyond day-level naming or numbering conventions. In the ISO 8601 standard, adopted for international data exchange, a week comprises exactly seven days beginning on Monday, with years containing 52 full weeks (364 days) plus one or two extra days, or occasionally 53 weeks (371 days) to align with the calendar year. This structure ensures continuity, as the week advances uniformly regardless of month or year lengths, resulting in most non-leap years spanning 52 weeks and one day (365 ÷ 7 ≈ 52.14), and leap years 52 weeks and two days. The seven-day framework persists due to its deep cultural entrenchment rather than precise astronomical synchronization, enabling consistent scheduling for work, rest, and religious observance across societies. While experimental alternatives like the Soviet five-day or six-day weeks were tested in the early 20th century, they failed to supplant the seven-day model owing to entrenched habits and coordination challenges.

Origins of the Seven-Day Cycle

The seven-day cycle originated in ancient , particularly among the Babylonians around the second millennium BCE, where it emerged from observations of the . The Babylonian month approximated 29.5 days, which they divided into four roughly equal phases—new moon, first quarter, , and last quarter—each spanning about seven days, providing a practical unit for timekeeping independent of solar years. This division aligned with the identification of seven prominent celestial bodies visible to the naked eye: the Sun, Moon, Mercury, Venus, Mars, Jupiter, and Saturn, which Babylonian astronomers associated with days in a recurring cycle, influencing later planetary naming conventions. Early textual evidence, such as references in the Assyro-Babylonian Epic of Gilgamesh dating back to the third millennium BCE, mentions seven-day periods, suggesting the cycle's antiquity in Sumerian and Akkadian traditions before full Babylonian formalization. The Babylonians marked every seventh day from the new moon as a shapattu or "evil day," a period of abstention from certain activities due to astrological omens, indicating a cultural recognition of the cycle's rhythm without a mandatory rest mandate. The cycle's transmission beyond Mesopotamia occurred through cultural exchanges, with evidence pointing to adoption by the in the first millennium BCE, possibly during or after the Babylonian exile in the 6th century BCE, though biblical texts like Genesis describe a creation week predating that event. Scholars note that while the Hebrew Sabbath emphasized rest on the seventh day as divinely ordained, the underlying continuous seven-day count likely drew from Mesopotamian precedents, as no earlier independent Hebrew calendrical evidence for a fixed week exists outside lunar month divisions. This integration transformed the astronomical cycle into a perpetual , resistant to resets at month ends, distinguishing it from purely lunar-tied observances in .

Terminology and Naming

Etymology of "Week"

The English word "week" derives from Middle English or weke, which in turn comes from wīcu or wucu, referring to a succession of days. This form traces to Proto-Germanic *wīkōn-, from a root *wik- or *weik- implying "turn," "change," or "succession," evoking the cyclical shift of days rather than the numerical seven-day span itself. Cognates in other include vika, wehha, and modern Dutch week, all sharing this Proto-Germanic origin and diverging from non-Germanic terms like Latin septimana (from septem, "seven"). The term's etymology thus highlights a conceptual emphasis on temporal in early Germanic speech, independent of the seven-day cycle's Mesopotamian or biblical . Other historical and archaic synonyms for "week" include "hebdomad," from Greek ἑβδομάς (hebdomas), denoting a group of seven or a period of seven consecutive days, and "sennight," an obsolete English contraction of "seven nights" referring to a week.

Names of the Days

The names of the days of the week in English stem from Anglo-Saxon translations of the Roman planetary nomenclature, where each day was linked to a celestial body or deity visible to ancient astronomers. Sunday, from Old English Sunnandæg, directly translates the Latin dies Solis (day of the Sun), honoring the central star in the solar system. Monday, from Monandæg, corresponds to dies Lunae (day of the Moon), reflecting the satellite's influence in early cosmology. Saturday preserves the Roman dies Saturni (day of Saturn), the outermost known planet to the ancients, associated with the god of agriculture and time; this retention occurred without Germanic substitution. The intermediate days underwent reinterpretation through , equating local gods to Roman counterparts via cultural during the Roman Empire's contact with northern tribes around the 1st to 5th centuries CE. derives from Tīwesdæg, invoking Tiw or Tyr, the one-handed war god akin to Mars, whose Latin day dies Martis emphasized martial prowess. , from Wōdnesdæg, names Woden or , the chief deity of wisdom and poetry, mapped onto Mercury (dies Mercurii), the messenger god. , Þunresdæg, honors Thunor or Thor, the thunder god paralleling (dies Iovis), ruler of the skies and oaths. , Frīgedæg, refers to Frige or Freya, goddess of love and , substituting for (dies Veneris), embodying and desire. This substitution pattern reflects interpretatio germanica, where tribes overlaid their pantheon onto imported Roman without altering the seven-day planetary sequence established by Hellenistic influences from circa 200 BCE.
English NameOld English FormRoman EquivalentAssociated Deity/Body
SundaySunnandægDies Solis
MondayMonandægDies Lunae
TuesdayTīwesdægDies MartisMars/Tiw ()
WednesdayWōdnesdægDies MercuriiMercury/Woden (wisdom)
ThursdayÞunresdægDies Iovis/Thor (thunder)
FridayFrīgedægDies Veneris/Frige (love)
SaturdaySæturnesdægDies SaturniSaturn
This table illustrates the Germanic adaptations, with data drawn from etymological analyses of post-Roman linguistic shifts. In , fidelity to Latin planetary roots persisted more closely, though altered Sunday to forms like French dimanche or Italian domenica, from dies Dominica (), prioritizing biblical resonance over solar worship by the 4th century CE. through retained lunae, Martis, Mercurii, Iovis, and Veneris derivations—e.g., Spanish martes (Mars), French jeudi ()—while Saturday often blended Saturni with influences as sábado. beyond English show partial divergences; modern German uses Mittwoch (midweek) for instead of a Woden derivative, reflecting medieval practical renaming around 1000 CE to avoid overt paganism. Semitic traditions diverged entirely from planetary etymologies, employing ordinal numbering tied to the cycle originating in ancient Israelite practices documented in Exodus 20:8-11. Hebrew designates Sunday as Yom Rishon (first day), from rosh (head or beginning), Monday Yom Sheni (second day), and so on to Friday Yom Shishi (sixth day), culminating in (rest), derived from the verb shavat (to cease) and instituted as the seventh day of cessation from labor circa 1400 BCE per biblical chronology. This numerical system, emphasizing sequence from , influenced Arabic names like al-ahad (the first) for , though Friday al-jumu'ah (day of congregation) highlights communal . Such contrasts underscore how cultural priorities—astrological in Indo-European lineages versus covenantal in Abrahamic—shaped independent of the shared seven-day framework.

Days of the Week

Sequence and Planetary Associations

The sequence of the seven days of the week derives from ancient astrological practices associating each day with one of the seven classical celestial bodies—Saturn, , Mars, , , Mercury, and —known as in antiquity. In the Roman planetary week, these correspond to (Saturn), (Sun), (Moon), Tuesday (Mars), (Mercury), (), and (). This ordering emerged from the Hellenistic system of , where the 24 hours of each day were successively ruled by the seven bodies in the Chaldean sequence, ordered by their apparent speeds from : Saturn (slowest), , Mars, Sun, , Mercury, (fastest). Under this system, the ruling body for the first hour of a day determines the day's planetary ruler, with hours cycling through the Chaldean order. Since 24 hours divided by 7 yields a of 3, the first hour of the following day falls three positions ahead in the sequence, producing the observed weekly order starting from Saturn's day. For instance, after Saturn rules Saturday's first hour, the cycle advances such that begins with the Sun, with the , and so forth, looping back after to Saturn. This mechanism, documented in Hellenistic and early Roman astrological texts, standardized the planetary week despite debates over its precise Babylonian, Egyptian, or Greco-Egyptian origins.
DayPlanetary Ruler
SaturdaySaturn
SundaySun
MondayMoon
TuesdayMars
WednesdayMercury
Thursday
Friday

Variations in Week Start and Cultural Designations

The designation of the first day of the week differs across cultures and regions, primarily between and , reflecting historical, religious, and practical influences. The international standard ISO 8601 defines the week as beginning on , with week 01 containing the first of the year; this convention is adopted in most European countries, parts of , and aligns with the typical Monday-to-Friday workweek structure. In contrast, calendars in the United States, , , , and much of the start the week on , a practice rooted in traditions where follows the (Saturday) as described in the Hebrew Bible's account of creation, with resting on the seventh day. This start gained formal recognition in the under Emperor Constantine's 321 AD edict establishing as a day of rest, influencing Western calendrical norms. Cultural designations further vary; for instance, in several Muslim-majority countries such as and the , the week traditionally begins on , with weekends often spanning Thursday and to accommodate 's Jumu'ah as the primary day of communal , though some nations like start on to emphasize 's religious precedence. In , despite the on , the civil week starts on to synchronize with international business practices. These variations impact practical applications, such as software date formatting and international scheduling, where ISO 8601's Monday start predominates for , while regional calendars preserve Sunday for cultural continuity. No universal consensus exists beyond ISO standards, as designations stem from entrenched religious observances rather than empirical uniformity.

Historical Origins and Development

Ancient Near East and Mesopotamian Roots

The seven-day cycle emerged in Mesopotamian civilizations, particularly among the Sumerians and Babylonians, rooted in astronomical observations of the seven celestial bodies visible to the : the Sun, the , Mercury, , Mars, , and Saturn. These bodies were linked to deities in , influencing the division of time into seven-unit periods for and divinatory purposes, with each day dedicated to one such entity. The number seven held sacred numerological importance, appearing in exorcisms, temple offerings, and literary works like the , which references seven-day intervals dating to origins in the third millennium BCE. Archaeological and textual evidence from indicates early use of seven-day durations in ceremonial contexts, such as the seven-day festival for dedicating a seven-roomed temple tower by , priest-king of , circa 2600 BCE. Akkadian records from around 2300 BCE show astrological decrees emphasizing seven-day significance, predating broader adoption. Babylonian lunisolar calendars, operational from the second BCE, approximated months of 29–30 days with segments of seven days, including periodic "holy-days" or "evil-days" on the 7th, 14th, 21st, and 28th, marked by abstentions from labor and omens due to perceived unfavorable planetary influences. These practices did not constitute a perpetual, continuous seven-day week detached from lunar phases, as months ended with residual days to align with the 29–30-day lunation, interrupting strict cycles. Instead, Mesopotamian systems featured quasi-weekly divisions tied to celestial and patterns, providing a foundational astronomical and cultural framework for later developments in the . No direct evidence exists for a standardized weekly rest akin to the later in these contexts; rests were episodic and omen-based rather than recurrent every seventh day regardless of position. This periodicity, however, reflects causal links to observable heavenly motions, privileging empirical sky-watching over arbitrary divisions.

Jewish Adoption and Sabbath Institution

The institution of the Sabbath marked the Jewish transformation of the seven-day cycle into a sacred temporal framework, designating the seventh day——as a day of complete cessation from labor to commemorate God's rest after creation. The attributes the Sabbath's origin to the , where the seventh day is sanctified following six days of divine activity (Genesis 2:2–3). This was codified as a covenantal commandment in the Decalogue given at , requiring to "remember the Sabbath day, to keep it holy" by refraining from work, extending the to household members, servants, , and resident aliens (Exodus 20:8–11). Unlike Mesopotamian "shapattu" observances, which aligned with lunar phases (e.g., the 7th, 14th, 21st, and 28th days) and often connoted ill omens or appeasement rituals rather than routine rest, the Jewish enforced a perpetual, non-lunar weekly cycle focused on affirmative sanctification and human-divine imitation of creation's completion. Babylonian records, such as those from the Neo-Babylonian period (circa 626–539 BCE), describe shapattu as days of abstention from certain activities amid festival contexts, but lack evidence of a continuous seven-day reckoning detached from the moon's phases or emphasizing universal rest. The Torah's pre-Sinai episode further illustrates an operational seven-day pattern, with provisions doubling on the sixth day and spoiling attempts on the seventh, suggesting the cycle's embeddedness in Israelite practice by the late second millennium BCE. Archaeological and textual evidence for routine weekly Sabbath observance in pre-exilic Israel remains limited, with prophetic rebukes (e.g., Amos 8:5, Isaiah 1:13) implying irregular compliance rather than institutional uniformity before the monarchy's fall in 586 BCE. Some scholars posit reinforcement during the Babylonian exile, when Judean captives encountered formalized Mesopotamian calendrical intervals, potentially standardizing the continuous cycle post-return under Persian rule (539–332 BCE), as reflected in Nehemiah 13:15–22's enforcement against Sabbath violations. Nonetheless, the Sabbath's endurance as a marker of Jewish identity—uninterrupted through diaspora and persecution—distinguished it from pagan counterparts, embedding the seven-day week as a theocentric rhythm resistant to imperial calendars.

Achaemenid and Hellenistic Transmission

The , following its conquest of in 539 BCE, incorporated diverse subjects including Jewish exiles who had adopted the Babylonian-derived seven-day cycle centered on the . the Great's edict around BCE permitted Jewish return to while allowing communities to remain in and Persian territories, where documentary evidence from the mid-fifth century BCE, such as the Murashu archive, indicates ongoing observance as a marker of Judean identity. Persian administrative tolerance of local customs preserved this cycle without official imperial adoption, as the Achaemenid calendar featured numbered days in lunisolar months divided unevenly, lacking formal recognition of a hebdomadal structure. Under Achaemenid rule, Jewish texts like 56:1–7 reflect expectations of Gentiles joining in practices, suggesting within the empire's multicultural framework, though no direct evidence shows restructuring their timekeeping around seven days. The empire's stability facilitated continuity of the cycle among Jewish populations, numbering perhaps tens of thousands in alone, providing a conduit for its later westward spread. In the Hellenistic era after Alexander the Great's conquests (333–323 BCE), Seleucid and Ptolemaic rulers governed former Persian domains with substantial Jewish diasporas in centers like and Antioch, where the seven-day persisted amid Greek lunar calendars that lacked a fixed weekly division. Greek exposure intensified through these communities and Eastern , culminating in the emergence of the planetary week in Hellenistic by the second century BCE, which fused the numeric seven-day cycle with astrological associations of days to the seven visible "planets" (sun, , and five wanderers). This syncretic form, evidenced in parapegmata and astrological texts, marked the cycle's into Greek terminology as hebdomas, facilitating its transmission beyond Jewish contexts. Hellenistic astrologers, drawing on Babylonian precedents preserved via Persian intermediaries, popularized the sequence, with days sequentially ruled by planetary deities in a Chaldean order (Saturn, Jupiter, Mars, Sun, Venus, Mercury, Moon). Jewish resistance to syncretism, as in the Maccabean Revolt (167–160 BCE) against Seleucid impositions, nonetheless ensured the cycle's visibility, contributing to its eventual integration into broader Mediterranean time reckoning by the late Hellenistic period.

Roman Integration and Early Spread

The seven-day planetary week, originating from Hellenistic astrological traditions blending Babylonian and Egyptian influences, first appeared in and during the late first century BCE, as evidenced by epigraphic and literary records. This system assigned days to the seven celestial bodies visible to the —Sun, , Mars, Mercury, , , and Saturn—in a sequence derived from their purported speeds and mythological hierarchies, with Romans substituting their own deities for foreign ones, such as dies Martis (day of Mars) for and dies Veneris (day of Venus) for . Unlike the traditional Roman nundinae, an eight-day market cycle used for civil and commercial purposes since the early , the seven-day week initially functioned primarily in astrological, religious, and private contexts rather than official calendrical reckoning. Integration accelerated in the early imperial period through exposure to Eastern cults, Jewish diaspora communities, and Greco-Roman intellectuals, with the week appearing in horoscopes, almanacs, and personal notations by the first century CE. Literary sources, including Dio Cassius, reference its use among elites for timing rituals and predictions, while archaeological finds like Pompeian from 79 CE denote days by planetary names, indicating informal amid the empire's cultural . The system's appeal lay in its alignment with observable astronomy and numerological traditions, facilitating its persistence alongside the nundinae without immediate displacement of Roman civic rhythms. Official endorsement came under Emperor Constantine I in 321 CE, who decreed the seven-day week for imperial administration, designating Sunday (dies Solis) as a day of rest to honor the Sun while accommodating Christian observance of the , thereby bridging pagan and emerging Christian practices. This edict marked a causal turning point, embedding the week in state calendars and accelerating its supplanting of the nundinae, which faded by the late fourth century as evidenced by the absence of market day notations in later inscriptions. Early spread beyond Italy occurred via military legions, trade routes, and proselytizing religions, with papyri from and inscriptions from and Britain attesting to planetary day usage by the second century CE in provincial contexts. Jewish and Christian communities further propagated it, as seen in datings of events in Greek texts from the first century CE, while astrologers disseminated the cycle across the and Mediterranean frontiers. By the fourth century, amplified diffusion, with the week appearing in over 100 Latin and Greek epigraphic records empire-wide, reflecting its transition from marginal import to ubiquitous temporal framework sustained by institutional enforcement rather than mere cultural osmosis.

Islamic Formulation and Expansion

The seven-day week was incorporated into early Islamic practice during the Prophet Muhammad's time in following the Hijra in 622 CE, building on pre-existing awareness of the structure among Arabian tribes influenced by Jewish communities. While pre-Islamic employed a without a strictly defined weekly cycle tied to planetary names, the adoption of a seven-day division aligned with the affirmation of creation over six days followed by rest, echoing precedents but without mandating a equivalent. Instead, (al-Jum'ah, meaning "day of gathering") was designated for obligatory congregational prayer (Jumu'ah), as commanded in Quran 62:9-10, which instructs believers to cease trade and assemble for worship upon hearing the call. This formulation differentiated Islamic observance from the Jewish and Christian , possibly selected for practical reasons such as coinciding with Medina's market day, thereby integrating communal, economic, and religious functions. The nomenclature for the days reflected this : numerical designations for most (e.g., al-ahad for "first" corresponding to , al-ithnayn for "second" or , up to al-khamis for "fifth" or ), culminating in al-jum'ah for and as-sabt (borrowed from Hebrew ) for . This system, formalized under 's leadership around 622-632 CE, emphasized Friday's primacy without altering the core seven-day sequence, which had diffused into Arabia via trade and Jewish settlements rather than originating indigenously. Early hadiths record the first Jumu'ah prayer led not by Muhammad but commanded by him during the migration, underscoring its institutionalization as a weekly pillar distinct from daily salat. With the Islamic conquests commencing after Muhammad's death in 632 CE under the Caliphs, the seven-day week expanded across the rapidly growing empire, standardizing timekeeping in administration, markets, and religious life from the to Persia and beyond. By the Umayyad period (661-750 CE), this structure supplanted or integrated with local systems—such as Egypt's decanal divisions or Persia's Zoroastrian lunar-solar calendars—facilitating unified fiscal and judicial calendars tied to observances. The Abbasid era (750-1258 CE) further entrenched it through scholarly translations and trade networks, influencing regions like and the where Hellenistic planetary weeks had partial foothold but gained religious reinforcement via . This dissemination, driven by caliphal decrees and Quranic imperatives, contributed to the week's near-universal adoption in Muslim-majority areas by the , independent of solar year alignments.

Global Adoption and Regional Variations

Introduction to East Asia

In traditional n calendrical systems, centered on the lunisolar , there was no native seven-day week; time was divided into lunar months of approximately 29.5 days, solar terms marking seasonal changes, and a continuous numbering days via combinations of ten and twelve , yielding a 60-day period without weekly interruptions. This structure, originating in the around 1600–1046 BCE and refined under the (206 BCE–220 CE), emphasized cyclical agricultural and ritual timing over fixed weekly cycles, with shorter divisions like the ancient 10-day xun (旬) used sporadically for administrative purposes but not as a standard week. , Korea, and other regions adopted variants of this system, integrating it with local lunar-solar adjustments, but retained the absence of planetary or Sabbath-based weekly nomenclature until external influences. The seven-day week first appeared in East Asia through indirect Hellenistic and Persian transmissions along trade routes, with records indicating its sporadic use in during the Eastern Jin dynasty (317–420 CE), where it was linked to astrological observations rather than religious observance. Further attempts at integration occurred under the (550–577 CE) and (618–907 CE), influenced by Manichaean or Nestorian Christian communities, but these were short-lived, abolished amid dynastic shifts, and confined to elite or foreign contexts without altering broader societal rhythms. Jesuit missionaries in the Ming (1368–1644 CE) and Qing (1644–1912 CE) dynasties reintroduced the cycle for astronomical and evangelistic purposes, yet it remained marginal, as traditional almanacs (tongshu) prioritized the sexagenary system for daily forecasting and festivals. In , early knowledge via from existed by the 8th century, but practical disuse persisted until the 19th century. Widespread adoption of the seven-day week in coincided with 19th- and 20th-century modernization and Western calendrical reforms. integrated it during the (1868 onward), aligning with the Gregorian calendar's introduction on January 1, 1873 (Meiji 6-1-1), to synchronize with global commerce, education, and , naming days after planetary bodies (yōbi system: e.g., Nichiyōbi for ). formalized its use post-1911 Revolution, with the Republican era's (effective 1912) embedding the week for official, industrial, and international purposes, though traditional cycles endure in cultural contexts like zodiac compatibility. Korea followed suit under Japanese colonial administration (1910–1945), standardizing the week by the early 20th century, and reinforced it after independence with Gregorian alignment in 1954 for civil use. Today, East Asian nations observe the standard, with weeks starting on Monday in , , and , reflecting pragmatic convergence on global norms over indigenous traditions.

Incorporation in South and Southeast Asia

In South Asia, the seven-day week entered through Hellenistic astronomical influences following Alexander the Great's campaigns in the 4th century BCE, with integration into Indian systems by the Gupta period around the 5th century CE. Indian calendars adopted planetary nomenclature for the days—Ravivāra (Sunday, from Sūrya the Sun), Somavāra (Monday, from Candra the Moon), Mangalavāra (Tuesday, from Mangala Mars), Budhavāra (Wednesday, from Budha Mercury), Guruvara or Bṛhaspativāra (Thursday, from Bṛhaspati Jupiter), Śukravāra (Friday, from Śukra Venus), and Śanivāra (Saturday, from Śani Saturn)—mirroring Greco-Roman planetary associations adapted to Hindu deities. This astrological framework appears in texts like the Yavanajātaka (2nd century CE), a Sanskrit translation of Greek horoscopic astrology, indicating transmission via Indo-Greek kingdoms. Pre-colonial Indian utilized the saptaha (seven-day cycle) for and astrological purposes, though without a universal fixed rest day; observances varied by community, such as Hindu fasting on specific weekdays or Jaina upavasa cycles. Mughal rule from the reinforced the structure through Islamic emphasis on Jumu'ah ( congregational prayer), but did not introduce the cycle, as it predated widespread Muslim presence. British colonial administration in the standardized as the weekly holiday, aligning with Christian practices and facilitating governance, yet the planetary naming persisted in vernacular usage. In , the seven-day week arrived primarily via Indian during the CE, through Hindu-Buddhist trade networks establishing kingdoms like and . (Siam) and adopted Sanskrit-derived names, such as wan Ātit (Sunday) and wan Phut (Wednesday), integrated into Buddhist calendars for merit-making rituals on auspicious days. Indonesia's saw parallel adoption in Hindu-Buddhist eras, with Javanese pasaran systems interlocking five- and seven-day cycles for , as in the Balinese pawedan pawukon. Islamic expansion from the 13th century overlaid terms in Muslim-majority areas—e.g., Jumat for in —while retaining planetary roots elsewhere, with elevated for ṣalāh observance. Regional variations persist: most South Asian countries observe Sunday as the week’s start, while several Southeast Asian nations like and shifted to Monday under 20th-century international alignment, though cultural designations remain planetary or deity-linked. This incorporation blended with local lunar-solar calendars, prioritizing astrological over rigid economic divisions until modern standardization.

Establishment in Christian Europe and the West

The seven-day week, already practiced among Jewish and early Christian communities within the Roman Empire, gained civil standardization through Emperor Constantine's edict of March 7, 321 CE, which mandated rest on Sunday—"the venerable day of the Sun"—for urban magistrates, craftsmen, and residents, while permitting rural agricultural work to continue. This decree effectively elevated the planetary seven-day cycle over the traditional Roman eight-day nundinae market intervals, aligning state practice with the Christian observance of Sunday as the Lord's Day, a shift rooted in apostolic commemoration of Christ's resurrection rather than solely pagan solar veneration. Early Church Fathers, such as Ignatius of Antioch around 110 CE and Justin Martyr in the mid-second century, documented Sunday assemblies for worship, distinguishing them from Jewish Saturday Sabbath rest, though some communities initially observed both days. Following Constantine's conversion and the in 313 CE, which legalized Christianity, the seven-day week disseminated through imperial administration and missionary activity across the Western Roman provinces, supplanting residual pagan cycles by the late fourth century. The (circa 363–364 CE) canon 29 urged Christians to honor over , reflecting institutional consolidation amid debates over Judaizing practices. As the Western fragmented after 476 CE, monastic orders and bishops preserved the cycle via liturgical calendars, transmitting it to Germanic kingdoms during conversions, such as Clovis I's in 496 CE, which integrated Frankish elites into Roman-Christian temporal structures. In Anglo-Saxon , the 's De Temporum Ratione (725 CE) standardized week reckoning for ecclesiastical computation, embedding it in insular computus traditions. By the early medieval period, the seven-day week was ubiquitous in Christian , with planetary day names Latinized and adapted—e.g., dies Solis for retained in , while Germanic tongues substituted Norse deities for midweek days (Tiwesdæg for , Wōdnesdæg for ), preserving the sequence without altering the cycle's length or analogue. Charlemagne's Admonitio Generalis (789 CE) enforced uniform liturgical observance, including rest, across the Carolingian realm, linking week structure to imperial unity and agrarian rhythms where workweeks typically spanned six days with one for respite and worship. This establishment endured through feudal fragmentation, as evidenced by entries (1086 CE) referencing weekly market days aligned to the Christian cycle, demonstrating its role in economic and legal continuity despite regional naming variations. Scholarly analyses confirm that "globalized" the week in by the ninth century, overriding pre-Christian lunar or market-based intervals through Church authority, though peripheral areas like retained pagan overlays until full conversion by the eleventh century.

Modern Week Numbering and Standardization

ISO Week Date System

The ISO week date system, part of the international standard for data interchange, represents dates using a year number, week number, and day-of-week designation, with weeks defined as seven consecutive days starting on . This format, denoted as YYYY-Www-D (where Www is the two-digit week number from 01 to 53 and D is 1 for through 7 for ), facilitates unambiguous machine-readable date handling in , , and applications. The numbering rule designates week 01 as the week containing the first of the year, ensuring it includes at least four days of and always encompasses January 4. Equivalently, it is the earliest week with a (four or more) of its days in the , preventing short initial weeks of one, two, or three days from being labeled as week 01. Most years contain 52 weeks (364 days), but 53-week "long" years occur when the Gregorian year has 371 days aligned such that the extra week fits the rule—specifically, in common years starting on or (in ) on or . The ISO year may differ from the Gregorian year by one for dates near the turn of the year; for instance, –31 in a year starting on belong to the next ISO year, while in a year ending appropriately may start the following year's week 01. This system diverges from North American conventions, where weeks often start Sunday and the first week may include partial days from December, leading to inconsistencies in cross-border data exchange. Adoption has grown since the standard's evolution from ISO 8601:1988, with widespread implementation in software libraries (e.g., programming functions like WEEKNUM with ISO mode), European business practices, and international standards bodies to promote interoperability and reduce errors in scheduling and reporting. For example, quarters in the ISO system consistently feature 13 weeks for the first three, with the fourth having 13 or 14, aiding fiscal planning.
AspectISO Week RuleCommon Alternative (e.g., U.S. Week)
Week StartMondayOften Sunday
Week 01 DefinitionContains first (≥4 days in January)Includes , regardless of length
Year Length52 or 53 weeksTypically 52, with variable partial weeks
Day Designation1= to 7=Varies; often 1=Sunday to 7=Saturday

Alternative Numbering Methods

In addition to the ISO 8601 standard, which defines weeks starting on Monday with week 1 containing at least four days of the new year (specifically, the week with January 4), several alternative week numbering methods are employed, primarily in regional, software, and industry-specific contexts. These variations arise from differences in the designated first day of the week and the criteria for assigning week 1, often leading to discrepancies in week counts between years or systems. For example, a given date may fall in week 1 under one method but week 52 or 53 under another, particularly near year transitions. Such alternatives persist despite ISO 8601's adoption as an international standard in 1988, due to entrenched conventions in commerce, epidemiology, and computing. The predominant alternative in is the system where weeks begin on , and week 1 is the week containing , regardless of its length. This contrasts with by prioritizing alignment over full-week thresholds, resulting in potential partial weeks at year starts or ends. In years where falls late in the ISO week (e.g., a Thursday), the system may assign an extra week (53 total) that ISO does not, as seen projected for 2027 where late December 2026 dates differ in numbering. This -start convention aligns with cultural practices in the and , where is treated as the week's outset for and reporting, though week numbering is less uniformly standardized than in ISO-adopting regions. Software implementations, such as Excel's WEEKNUM function with system parameter 1, operationalize this by numbering weeks from the Sunday-inclusive period containing . Fiscal week numbering, common in retail and manufacturing, further diverges by structuring the year around 52 full weeks (364 days) plus an occasional 53rd week to reconcile with the 365- or 366-day calendar. The National Retail Federation's 4-4-5 calendar exemplifies this, dividing each quarter into three "months" of 4, 4, and 5 weeks (13 weeks total per quarter), with weeks typically starting on Sunday or Saturday to facilitate consistent sales comparisons across years. The fiscal year often commences on the first Sunday nearest January 1 or a fixed retail anchor like the Saturday closest to December 31, ensuring holidays fall in predictable weeks and avoiding mid-week year-ends that distort quarterly data. A 53-week year occurs every five to six years when needed to align with the Gregorian calendar, such as in 2026 under some implementations. This method prioritizes economic periodicity over astronomical alignment, reducing variability in period-over-period metrics but requiring adjustments for tax or statutory reporting. Other software-defined variants, such as Excel's additional WEEKNUM systems (e.g., parameter 11 for Monday-start with week 1 as the first full Monday of the year), provide flexibility for localized or custom needs but can introduce interoperability issues in global data exchange. Similarly, epidemiological surveillance in the , via the CDC, uses Sunday-start weeks with week 1 defined as the first with more than half its days in the , aiding consistent tracking of events like outbreaks. These alternatives underscore the tension between standardization and practical utility, with favored for cross-border consistency while regional systems endure for domestic applications.

Weeks in Other Calendar Systems

Pre-Modern Non-Julian Calendars

The Babylonian , predating the Julian reform by over two millennia, featured an intermittent seven-day cycle known as sabbatu, where every seventh day from was designated a day of abstinence or ominous portent, as documented in tablets from the eighteenth century BCE. This structure approximated lunar phases—roughly four seven-day segments per 29- or 30-day month—and influenced subsequent Near Eastern timekeeping, though it lacked the continuous, planetary-named cycle of later adoption. The Hebrew , operational by the first millennium BCE, formalized the continuous seven-day week with the (Shabbat) as the seventh day of rest, a practice rooted in biblical creation accounts and maintained unbroken regardless of intercalary adjustments to align lunar months with the solar year. While possibly drawing from Mesopotamian precedents encountered during the Babylonian (circa 586–539 BCE), Hebrew observance emphasized theological fixity over astronomical variability, with days numbered sequentially from the and no named weekdays until later Hellenistic influences. In contrast, the ancient Egyptian solar calendar divided its 365-day year into 12 months of 30 days each, plus five epagomenal days, employing a ten-day administrative week (phyle or decade) tied to work rotations among priestly or labor groups, with rest following nine consecutive workdays. This decimal structure reflected Nile flood cycles and decanal star risings rather than septenary divisions, persisting alongside occasional lunar observances without integrating a seven-day rhythm until Greco-Roman contacts. Other pre-modern non-Julian systems, such as the traditional Chinese , eschewed weekly cycles altogether, relying instead on a ten-day xun for administrative purposes within sexagenary day counts, until foreign introductions in the nineteenth century. Similarly, pre-Islamic Arabian lunar reckoning incorporated a nascent seven-day framework, which the (established 622 CE) retained as a pure lunar system of 354 or 355 days, designating (Jumu'ah) for communal while drifting relative to seasons. These variations highlight how week lengths often derived from local , labor needs, or celestial markers, independent of solar year reforms like the Julian.

20th-Century Reforms and Failed Alternatives

In the , the Bolshevik government under implemented a radical reform to the traditional seven-day week as part of efforts to industrialize and eliminate religious influences. On August 24, 1929, the decreed the introduction of the nepreryvka, or continuous work week, initially as a five-day cycle consisting of four workdays followed by one rest day, designed to ensure uninterrupted factory production. This system replaced the seven-day week, with days assigned colors or symbols (e.g., red, yellow, green, blue, violet) to denote work or rest, and workers' rest days staggered across the cycle to prevent collective downtime. The reform aimed to boost productivity by approximately 15-20% through constant operation of machinery and to eradicate the Christian , particularly , which was seen as a remnant of religious superstition hindering socialist progress. Implementation began experimentally in select industries in October 1929 and expanded nationwide by early 1930, affecting over 70% of industrial workers by mid-decade. However, the staggered rest days severely disrupted life, as spouses and children often worked and rested on different days, leading to and declining morale. Productivity gains were minimal or negligible, with reports indicating no significant increase in output and even some decreases due to worker fatigue and logistical challenges in scheduling. Religious observance persisted underground, and the system complicated coordination for markets, transportation, and cultural events. By December 1930, partial reversals allowed some synchronization, but dissatisfaction mounted. In response to these failures, the Soviet government transitioned to a six-day work week on , , comprising five workdays followed by a universal rest day on , restoring a common day off while maintaining industrial continuity. This adjustment addressed family and social disruptions but still prioritized production over traditional rhythms. The six-day week endured until , , when, amid preparations for and recognition of the need for worker cohesion, the seven-day week with off was reinstated, effectively acknowledging the impracticality of the reforms. No comparable large-scale implementations occurred elsewhere, though international bodies like of Nations reviewed proposals in the 1930s that occasionally suggested week adjustments, but these focused more on monthly structures and failed to gain traction due to entrenched cultural and religious attachments to the seven-day cycle.

Cultural, Religious, and Practical Implications

Religious and Sabbath Observances

In , the , known as , falls on the seventh day of the week, commencing at sunset on and concluding at sunset on , during which observant refrain from work, engage in prayer, study , and share festive meals to commemorate divine rest after creation. This observance stems from the Fourth Commandment in Exodus 20:8-11, mandating rest on the seventh day as a perpetual sign of the covenant between God and . Most Christian traditions shifted primary weekly observance to Sunday, termed the , to honor Christ's resurrection, which occurred on the first day of the week according to the Gospels (e.g., Matthew 28:1). Early Christian writings, such as the (c. 70-120 CE) and of Antioch's Epistle to the Magnesians (c. 110 CE), describe communal worship, , and rest on , distinguishing it from Jewish practices while retaining elements of cessation from labor. By the fourth century, Emperor Constantine's in 321 CE formalized as a day of rest across the , aligning civil law with emerging ecclesiastical custom. In , Friday serves as the primary day for weekly congregational prayer, known as Jumu'ah, performed after noon in mosques worldwide, supplanting the individual Zuhr prayer and featuring a sermon () on religious and moral topics. The (Surah Al-Jumu'ah 62:9-10) instructs believers to hasten to prayer upon hearing the call, suspending commerce temporarily to emphasize communal unity and spiritual reflection, though Friday is not a full day of rest like the . Certain Christian denominations, notably Seventh-day Adventists, adhere to Saturday as the , viewing it as an unchanged commandment from creation (Genesis 2:2-3) and rejecting the Sunday shift as a later lacking direct scriptural mandate for abrogation. Adherents typically attend services from Friday evening through , avoiding secular work and focusing on , nature study, and acts of mercy, with global membership exceeding 22 million as of 2023. Non-Abrahamic faiths like and adopted the seven-day week through but do not enforce a universal weekly ; instead, weekdays may hold devotional significance, such as on Mondays for Lord Shiva in or merit-making on days (lunar-based, not strictly weekly) in . These practices prioritize cyclical lunar or festival observances over a fixed hebdomadal rest day.

Economic and Workweek Structures

The five-day workweek, typically spanning Monday through Friday with Saturday and Sunday designated for rest, forms the backbone of labor structures in most Western economies, driven by empirical observations that periodic downtime enhances overall productivity by allowing recovery from physical and mental fatigue. This model gained traction during the , where initial six-day schedules led to documented increases in industrial accidents and diminished output due to exhaustion, prompting employers to experiment with shorter cycles for sustained efficiency. By the early , economic rationale shifted toward balancing labor input with consumption capacity, as evidenced by Henry Ford's 1926 adoption of a five-day, at plants, which doubled prior wages in 1914 to retain skilled workers while recognizing that leisure time enabled employees to afford mass-produced goods like automobiles, thereby closing the production-consumption loop essential to Fordist economics. Legislative codification followed industrial precedents, with the U.S. Fair Labor Standards Act of 1938 establishing premiums for hours exceeding 40 per week, indirectly standardizing the five-day framework by incentivizing employers to avoid penalty rates through efficient scheduling rather than extended daily shifts. Econometric analyses of this transition reveal causal links between reduced weekly hours and metrics such as lower —Ford reported fewer sick days post-implementation—and higher long-term output per worker, as rest periods mitigated the on labor observed in pre-1920s factory data where correlated with error rates up to 20% higher on later weekdays. In contemporary terms, controlled trials of compressed workweeks, including four-day variants maintaining 40 total hours, have shown no decline and reductions in turnover by over 50% alongside 65% fewer sick days, attributing gains to improved focus and morale rather than mere hour cuts. Globally, workweek structures diverge to integrate religious or cultural rest days, influencing economic coordination; for example, several Gulf states employ a Sunday-to-Thursday to align with communal prayers, minimizing disruptions to while preserving domestic labor rhythms tied to Islamic economic practices that prioritize weekly over uniform weekends. These variations impose coordination costs in multinational operations, such as staggered deadlines, but empirical from cross-border firms indicate negligible aggregate productivity impacts when adjusted for local holidays, as standardized tools like weeks facilitate fiscal reporting across discrepancies. Economic modeling further underscores that rigid five-day adherence optimizes capital utilization—machinery operates fewer idle days—yet flexible adaptations, as in service sectors with weekend shifts, sustain growth by matching peaks, with studies linking irregular scheduling to higher work-family conflict and volatility in hourly earnings that erode net output.

Criticisms, Debates, and Reform Proposals

The seven-day week has been criticized for its lack of alignment with natural astronomical cycles, such as lunar phases or solar months, rendering it an arbitrary construct that complicates scheduling and fails to divide evenly into the 365- or 366-day Gregorian year, causing holidays to shift weekdays annually. This misalignment contributes to inefficiencies in economic and administrative planning, as the seven resists subdivision into practical units like four- or five-day work periods without remainder issues. Critics argue that in secular modern societies, where strict observance has declined, the cycle's persistence lacks empirical justification and perpetuates outdated rhythms disconnected from productivity data or biological rest needs. Debates persist over the week's starting day, with North American conventions favoring Sunday—rooted in traditions where it marks the —while European and standards designate Monday as the first day to prioritize and workweek alignment. This discrepancy leads to inconsistencies in international software, calendars, and , as evidenced by programming challenges in handling week numbering across regions. The system, which numbers weeks from Monday and assigns weeks to years based on a Thursday rule, faces scrutiny for creating "week 53" anomalies in certain years and poor synchronization with Gregorian months, particularly and , which can split across ISO years. Proponents defend ISO for its utility in time-series data and logistics, yet detractors highlight its divergence from intuitive calendar expectations, exacerbating errors in fiscal reporting and cross-border coordination. Historical reform proposals to alter week length have uniformly failed due to social disruption and cultural entrenchment. The (1793–1805) replaced weeks with 10-day "decades," aiming for decimal rationality, but it eroded communal rest patterns and was abandoned after the for lacking practical adoption. Similarly, the experimented with a 5-day continuous workweek in 1929–1930, followed by a 6-day version until 1940, intending to boost industrial output by staggering rest days; however, it fractured family and social cohesion, as individuals often lacked shared off-days, leading to widespread dissatisfaction and reversion to the seven-day cycle by June 27, 1940. These efforts underscore causal resistance from entrenched religious and habitual norms, outweighing ideological drives for uniformity. Modern proposals largely preserve the seven-day framework while compressing work hours—such as U.S. bills for a 32-hour week (2024) or Mexico's 40-hour limit debates (2025)—focusing on gains without restructuring the cycle itself, as evidenced by pilot studies showing sustained output but no consensus on length changes. Radical abolitions remain marginal, with analyses attributing the week's durability to its self-perpetuating social inertia rather than inherent optimality.

References

  1. https://www.math.net/week
  2. https://www.merriam-webster.com/dictionary/week
  3. https://www.astronomy.com/science/why-are-there-7-days-in-a-week-thank-the-babylonians/
  4. https://www.almanac.com/why-week-has-seven-days
  5. https://www.rmg.co.uk/stories/time/why-12-months-year-seven-days-week-or-60-minutes-hour
  6. https://www.timeanddate.com/calendar/days/first-day-of-the-week.html
  7. https://www.timeanddate.com/calendar/days/
  8. https://www.britannica.com/science/week
  9. https://www.timeanddate.com/calendar/days/7-days-week.html
  10. https://www.iso.org/iso-8601-date-and-time-format.html
  11. https://www.calendar.com/blog/the-origin-of-our-modern-time-structure-the-7-day-week/
  12. https://african-research.com/research/the-babylonians-developed-the-7-days-of-the-week-system-2300-years-before-the-biblical-christ-was-born/
  13. https://adsabs.harvard.edu/full/1939PA.....47..175C
  14. https://ideas.tikvah.org/mosaic/observations/when-did-jews-settle-on-the-seven-day-week
  15. https://www.academia.edu/94531888/Seven_Day_Cycle_and_the_Origin_of_the_Sabbath_in_its_Ancient_Oriental_Context
  16. https://www.etymonline.com/word/week
  17. https://www.merriam-webster.com/dictionary/hebdomad
  18. https://www.merriam-webster.com/dictionary/sennight
  19. https://www.merriam-webster.com/wordplay/etymologies-for-every-day-of-the-week
  20. https://www.almanac.com/origin-day-names
  21. https://theconversation.com/explainer-the-gods-behind-the-days-of-the-week-87170
  22. https://www.vikingeskibsmuseet.dk/en/professions/education/viking-age-people/the-names-of-the-weekdays
  23. https://www.dictionary.com/e/french-romance-language-week-days/
  24. http://lp.eteacherhebrew.com/lp_modern_hebrew_weekdays-en.html?blog=1
  25. https://biblicalhebrew.org/hebrew-days-week.aspx
  26. https://blogs.fu-berlin.de/zodiacblog/2022/05/02/the-origins-of-the-planetary-week/
  27. https://www.renaissanceastrology.com/planetaryhoursarticle.html
  28. https://www.practicaltheurgy.com/planetary-hours-and-planetary-week/
  29. https://sevenstarsastrology.com/planetary-days-and-hours-in-hellenistic-astrology/
  30. https://www.timeanddate.com/calendar/days/monday.html
  31. https://museum.seiko.co.jp/en/knowledge/trivia07/
  32. http://www.todayifoundout.com/index.php/2015/03/week-starts-sunday/
  33. https://www.abc.net.au/news/2019-08-18/which-day-do-you-consider-the-start-of-the-week/11346348
  34. http://chartsbin.com/view/41671
  35. https://www.quora.com/Calendars-How-does-the-first-day-of-the-week-differ-around-the-world
  36. https://www.reddit.com/r/AskHistory/comments/1fwy3m3/when_did_the_seven_day_week_become_so_universal/
  37. https://medium.com/chryptianity-revealed/the-babylonian-genesis-of-time-addd2443c753
  38. https://www.ministrymagazine.org/archive/1980/08/archeology-and-the-sabbath
  39. https://www.thetorah.com/article/how-and-when-the-seventh-day-became-shabbat
  40. https://reformjudaism.org/jewish-holidays/shabbat/mysterious-origins-sabbath
  41. https://www.journals.uchicago.edu/doi/pdf/10.1086/470656
  42. https://www.nature.com/articles/011363b0
  43. https://bulletin.hds.harvard.edu/a-very-special-and-mysterious-day/
  44. https://brill.com/view/journals/jaj/16/1/article-p29_2.xml
  45. https://www.researchgate.net/publication/383796768_The_Sabbath_in_Judean_Communities_during_the_Mid-fifth_Century_BCE_Onomastic_Evidence
  46. https://www.academia.edu/64176267/Judean_Identity_during_the_Exile_Concluding_Deals_on_a_Sabbath_in_Babylonia_and_Egypt_under_the_Neo_Babylonian_and_the_Achaemenid_Empires
  47. https://www.iranicaonline.org/articles/hafta-week-history-of-the-weeky-calendar-in-iran-1/
  48. https://www.iranicaonline.org/articles/judeo-persian-communities-ii-achaemenid-period/
  49. https://jewishjournal.com/commentary/columnist/369369/how-ancient-persians-essentially-saved-judaism-as-we-know-it-today/
  50. https://cojs.org/overview-_jews_and_judaism_in_the_greco-roman_period/
  51. https://www.ucl.ac.uk/arts-humanities/hebrew-jewish/research/research-projects/research-project-archive/seven-day-week-roman-empire-and-near-east
  52. https://online.ucpress.edu/SLA/article/3/2/128/67651/Christianizing-the-Planetary-Week-and-Globalizing
  53. https://www.crowl.org/lawrence/time/days.html
  54. https://refubium.fu-berlin.de/bitstream/fub188/37017/5/Ch.1%2520Seven-day%2520week.pdf
  55. https://brill.com/display/book/edcoll/9789004459694/BP000011.xml?language=en
  56. https://www.understanding-islam.com/why-did-muslims-adopt-a-7-day-week/
  57. https://islamqa.info/en/answers/110226
  58. https://www.whyislam.org/fridayprayers/
  59. https://www.answering-islam.org/Books/MW/friday.htm
  60. https://www.oursunnah.com/p/first-jumua
  61. https://historum.com/t/arabs-pre-islamic-days-of-the-week.35179/
  62. https://www.oxfordbibliographies.com/abstract/document/obo-9780199840731/obo-9780199840731-0211.xml
  63. https://www.abc.net.au/news/2022-01-05/how-did-the-seven-day-week-come-to-govern-our-lives/100672194
  64. http://www.chinaknowledge.de/History/Terms/calendar.html
  65. https://users.wfu.edu/moran/planets_y_powers.html
  66. https://www.ndl.go.jp/koyomi/e/history/calendar.html
  67. http://www.cjvlang.com/Dow/dowchin.html
  68. https://wildinjapan.wordpress.com/2016/11/01/seven-days-a-week/
  69. https://blog.chineseskill.com/2024/10/14/days-of-the-week-in-chinese/
  70. https://www.academia.edu/49161712/The_Origins_of_the_Seven_Day_Week
  71. https://history.stackexchange.com/questions/2318/when-was-the-concept-of-weekly-day-off-first-introduced-in-indian-subcontinent
  72. https://www.researchgate.net/publication/338232061_The_Calendars_of_Southeast_Asia_1_Introduction
  73. https://viss.wordpress.com/2017/03/27/days-of-the-week-in-southeast-asia/
  74. https://oxfordre.com/asianhistory/display/10.1093/acrefore/9780190277727.001.0001/acrefore-9780190277727-e-846
  75. https://www.ministrymagazine.org/archive/1950/05/pagan-sunday-observance
  76. https://digitalcommons.andrews.edu/cgi/viewcontent.cgi?article=1442&context=auss
  77. https://archive.gci.org/articles/sabbath-and-sunday-in-the-early-church/
  78. https://www.catholic.com/tract/sabbath-or-sunday
  79. https://www.ministrymagazine.org/archive/1977/01/sabbath-and-sunday-observance-in-the-early-church
  80. http://www.medievalgenealogy.org.uk/cal/medcal.shtml
  81. https://www.discovermiddleages.co.uk/medieval-life/origin-of-english-days-of-the-week
  82. https://groups.csail.mit.edu/mac/users/rauch/worktime/hours_workweek.html
  83. https://history.stackexchange.com/questions/21304/how-was-the-current-month-and-day-disseminated-to-the-townspeople-of-medieval-eu
  84. https://help.tableau.com/current/pro/desktop/en-us/dates_calendar.htm
  85. https://www.dimins.com/online-help/workbench/72/visual-integrator/what-is-iso-8601.html
  86. https://www.brepols.com/Data/Downloads/ISO8601_RULE_FOR_DEFINING_WEEKNUMBERS.pdf
  87. https://webspace.science.uu.nl/~gent0113/calendar/isocalendar_text_2.htm
  88. https://learn.microsoft.com/en-us/power-platform/power-fx/reference/function-weeknum
  89. https://www.timeanddate.com/date/week-numbers.html
  90. https://support.microsoft.com/en-us/office/weeknum-function-e5c43a03-b4ab-426c-b411-b18c13c75340
  91. https://devblogs.microsoft.com/oldnewthing/20160311-00/?p=93144
  92. https://www.epochconverter.com/weeknumbers
  93. https://discussions.apple.com/thread/255989892
  94. https://nrf.com/resources/4-5-4-calendar
  95. https://www.cpajournal.com/2022/03/16/how-long-is-a-year/
  96. https://weeknumbers.ampli.fi/
  97. https://source.colostate.edu/why-are-there-seven-days-in-a-week/
  98. https://www.museumofthebible.org/book-minute/the-seven-day-week
  99. https://egypt.mrdonn.org/calendars.html
  100. http://gyre.umeoce.maine.edu/physicalocean/Tomczak/science%2Bsociety/lectures/lecture7.html
  101. https://www.academia.edu/28840012/The_Structure_of_the_Chinese_Calendar
  102. https://aa.usno.navy.mil/faq/islamic
  103. https://www.history.com/articles/soviet-union-stalin-weekend-labor-policy
  104. https://www.cabinetmagazine.org/issues/61/wood.php
  105. https://www.amusingplanet.com/2022/04/how-soviet-union-tried-to-abolish.html
  106. https://www.familysearch.org/en/wiki/Soviet_Calendar
  107. https://www.saet.ac.uk/Christianity/Sabbath
  108. https://ffoz.org/messiah/articles/which-day-is-the-sabbath-day
  109. https://www.thegospelcoalition.org/reviews/a-brief-history-of-sunday/
  110. https://christianheritagefellowship.com/lords-day-early-christianity/
  111. https://www.ministrymagazine.org/archive/1941/03/how-sunday-observance-entered-the-church
  112. https://www.islam.org.uk/special-occasions/friday-jummah/
  113. https://yantar.ae/blog/the-importance-of-jumu-ah-friday-prayer-in-islam
  114. https://adventist.org/beliefs/official/the-sabbath
  115. https://adventistpublishing.org/mission-365/glow-tracts/why-church-on-saturday/
  116. https://library.webster.edu/holidays/hinduism
  117. https://www.history.com/articles/five-day-work-week-labor-movement
  118. https://teachingamericanhistory.org/document/henry-fords-five-day-week/
  119. https://blogs.loc.gov/inside_adams/2024/01/40-hours-5-days/
  120. https://www.scientificamerican.com/article/a-four-day-workweek-reduces-stress-without-hurting-productivity/
  121. https://www.epi.org/publication/irregular-work-scheduling-and-its-consequences/
  122. https://equitablegrowth.org/working-by-the-hour-the-economic-consequences-of-unpredictable-scheduling-practices/
  123. https://www.theatlantic.com/family/archive/2021/11/weeks-seven-days-david-henkin/620712/
  124. https://slate.com/human-interest/2014/05/abolish-the-week-the-case-against-dividing-time-into-seven-day-periods.html
  125. https://www.quora.com/It-is-very-confusing-that-some-wall-calendars-start-the-week-on-a-Monday-instead-of-a-Sunday-How-did-that-inconsistency-happen
  126. https://news.ycombinator.com/item?id=32975843
  127. https://calendars.fandom.com/wiki/ISO_week_date
  128. https://stackoverflow.com/questions/69023651/coding-iso-week-of-year-week-53-problems
  129. https://news.ycombinator.com/item?id=21883313
  130. https://www.atlasobscura.com/articles/why-cant-we-get-rid-of-the-7day-week
  131. https://www.pbs.org/newshour/politics/what-to-know-about-bernie-sanderss-bill-for-the-u-s-to-adopt-a-32-hour-workweek
  132. https://mexicobusiness.news/policyandeconomy/news/mexico-debates-16-proposals-cut-workweek-40-hours
  133. https://sabbathsentinel.org/2021/02/09/failed-attempts-to-change-the-seven-day-cycle/
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