Hubbry Logo
Long tonLong tonMain
Open search
Long ton
Community hub
Long ton
logo
7 pages, 0 posts
0 subscribers
Be the first to start a discussion here.
Be the first to start a discussion here.
Long ton
Long ton
Long ton
View on Wikipedia
from Wikipedia
Long ton
Unit systemImperial units, United States customary units
Unit ofMass
Symbollong ton
In base units2,240 lb
Conversions
1 long ton in ...... is equal to ...
   SI base units   1,016.047 kg
   Metric tons   1.016047 t
   Short tons   1.12 short tons (exactly)

The long ton,[1] also known as the imperial ton, displacement ton,[1][2] or British ton,[3] is a measurement unit equal to 2,240 pounds (1,016.0 kg). It is the name for the unit called the "ton" in the avoirdupois system of weights or Imperial system of measurements. It was standardised in the 13th century. It is used in the United States for bulk commodities.

It is not to be confused with the short ton, a unit of weight equal to 2,000 pounds (907.2 kg) used in the United States, and Canada before metrication, also referred to simply as a "ton".

Unit definition

[edit]

A long ton is defined as exactly 2,240 pounds. The long ton arises from the traditional British measurement system: A long ton is 20 long hundredweight (cwt), each of which is 8 stone (1 stone = 14 pounds). Thus, a long ton is 20 × 8 × 14 lb = 2,240 lb.

Unit equivalences

[edit]

A long ton, also called the weight ton (W/T),[1] imperial ton, or displacement ton, is equal to:

  • 2,240 pounds (1,016.0 kilograms; 1.0160 metric tons)
  • exactly 12% more than the 2,000 pounds of the North American short ton, being 20 long hundredweight (112 lb) rather than 20 short hundredweight (100 lb)
  • the weight of 35 cubic feet (0.991 m3)[2] of salt water with a density of 64 pounds per cubic foot (1.03 g/cm3)[1]

Usage around the world

[edit]

United Kingdom

[edit]

To comply with the practices of the European Union, the British Imperial ton was explicitly excluded from use for trade by the United Kingdom's Weights and Measures Act of 1985.[4][5] The measure used since then is the tonne, equal to 1,000 kilograms.

If still used for measurement, then the word "ton" is taken to refer to an imperial or long ton.[6]

United States

[edit]

In the United States, the long ton is commonly used in measuring the displacement of ships and the shipping of baled commodities[1] and bulk goods like iron ore and elemental sulfur.[citation needed]

International

[edit]

The long ton was the unit prescribed for warships by the Washington Naval Treaty of 1922; for example, battleships were limited to a displacement of 35,000 long tons (35,560 t; 39,200 short tons). The long ton is traditionally used as the unit of weight in international contracts for many bulk goods and commodities.[citation needed]

See also

[edit]
  • Short ton, equal to 2,000 lb (907.2 kg).
  • Ton
  • Tonnage, volume measurement used in maritime shipping, originally based on 100 cubic feet (2.83 m3).
  • Tonne, also known as a metric ton (t), equal to 1,000 kg (2,205 lb) or 1 Mg.

References

[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Long ton

View on Grokipedia
from Grokipedia
The long ton, also known as the imperial ton or British ton, is a unit of mass equal to exactly 2,240 pounds (approximately 1,016.05 kilograms). It is defined as 20 , with each long hundredweight consisting of 112 pounds. Originating from the traditional British system standardized in the Weights and Measures Act of 1824, the long ton derives its name from the "tun," a large cask used historically for measuring wine and other goods in medieval trade. This unit became prominent in the for bulk commodities like , iron, and shipping cargo. In contrast to the U.S. short ton of 2,000 pounds (907.18 kilograms) and the international metric tonne of 1,000 kilograms (approximately 2,204.62 pounds), the long ton is heavier than both the short ton and the metric tonne. Although the began in the 1960s, with the Weights and Measures Act 1985 consolidating the legal framework that makes the the primary unit for most —the long ton persists in specific non-legal contexts, such as for ship displacement and certain international markets influenced by British traditions. Its use underscores ongoing variations in global systems, particularly in maritime and engineering sectors.

Definition and Origins

Formal Definition

The long ton, also known as the imperial ton, is a unit of mass in the imperial and United States customary systems, defined precisely as 2,240 pounds . This definition establishes it as equivalent to 1,016.0469088 kilograms, providing a direct relation to the while maintaining its imperial foundation. The long ton is defined under the Weights and Measures Act 1985 as 2,240 pounds . However, under this act, it may only be used as a supplementary indication to the metric tonne in trade. In technical and international notations, it is often abbreviated as "lt" or "long tn" to distinguish it from other variants. The long ton finds primary application in the measurement of bulk commodities, including , , and shipping , where large-scale imperial calculations remain relevant in certain sectors.

Historical Development

The long ton derives its name from the "tun," an term referring to a large cask or barrel employed in the wine during . This unit originally denoted a measure rather than a fixed weight, but it gradually evolved to represent substantial quantities of goods in . In from the 12th to 18th centuries, the tun served as a standard for trading wine, oil, and , with a typical capacity of 252 wine gallons that equated to a variable weight of approximately 2,000 to 2,500 pounds, depending on the contents' and regional customs. This flexibility reflected the practical needs of medieval merchants, where the tun's weight was often estimated based on filled casks rather than precise scales, facilitating across . By the , the ton—stemming from the tun—had become synonymous with a large unit in shipping and bulk goods, weighing around 2,240 pounds in common English usage for capacity in vessels. The long ton was formally standardized as 2,240 pounds (20 hundredweights of 112 pounds each) under the Weights and Measures Act of 1824, which consolidated disparate local standards into the Imperial system to promote uniformity in British . This act, building on earlier reforms, aligned the ton with the avoirdupois pound and yard, ensuring consistency for domestic and colonial commerce. During the , the unit gained prominence in the coal and iron trades, where Britain's annual coal output surged from about 10 million long tons in the early 1800s to over 200 million by the late , underscoring its role in fueling economic expansion. Although the United Kingdom initiated metrication in 1965 through the Weights and Measures Act, aiming to adopt the tonne for most purposes, the long ton endured in specialized areas like maritime shipping and legacy industrial records, reflecting resistance to full transition in traditional sectors.

Conversions and Equivalences

Imperial and Avoirdupois Relations

The long ton, a unit within the imperial system of weights, is defined as 20 long hundredweight, with each long hundredweight comprising 112 avoirdupois pounds, yielding a total of 2,240 pounds. This structure positions the long ton as the standard "ton of 20 cwt" in the British imperial framework, emphasizing its foundational role in avoirdupois-based measurements for bulk commodities. Tied intrinsically to the avoirdupois system, the long ton derives from the avoirdupois pound, legally defined as exactly 0.45359237 kilograms since the 1959 international agreement. Additionally, it equates to 160 stones, as each stone measures 14 avoirdupois pounds, providing an alternative hierarchical breakdown within the same system for coarser quantifications. In practical imperial contexts like , the long ton facilitated measurements of produce such as hay, where a historical load equated to 18 or about 0.9 long tons. This usage underscored its utility for valuing and transporting staple crops before widespread metric adoption. The long ton is slightly heavier than the metric tonne by approximately 16 kilograms.

Metric and SI Conversions

The long ton is precisely equivalent to 1,016.0469088 kilograms in the , derived from its definition as exactly 2,240 pounds and the international standard for the pound as exactly 0.45359237 kilograms. This exact value stems from the 1959 agreement, which fixed the pound-kilogram relationship to align imperial and metric measurements. To derive the conversion step by step:
  1. One long ton equals 2,240 pounds (lb), as established in imperial standards.
  2. One pound equals exactly 0.45359237 kg.
  3. Multiply: 2,240×0.45359237=1,016.04690882{,}240 \times 0.45359237 = 1{,}016.0469088 kg.
This precise factor ensures accurate translations across systems without rounding errors in scientific or contexts. In SI units, the long ton corresponds to 1,016,046.9088 grams (g), since 1 kg = 1,000 g exactly. Relative to the (1,000 kg), it equates to approximately 1.016 metric tonnes, providing a close but distinct comparison for international comparisons. For practical applications in trade and commerce, the long ton is often approximated as 1,016 kg to simplify documentation and calculations. The general conversion equation is: Mass (kg)=long tons×1,016.0469088\text{Mass (kg)} = \text{long tons} \times 1{,}016.0469088 This formula allows direct computation while preserving the exact imperial-metric linkage.

Global Usage and Adoption

United Kingdom Practices

In the , the long ton remains permitted under a dual-unit system established by the Units of Measurement Regulations 1995, which mandate metric units as primary for while allowing , including the long ton, as supplementary indications on and in . This framework supports its retention for legacy purposes, though it is no longer the primary measure in most commercial transactions. The long ton continues to play a role in specific industries, particularly , where it is applied to displacement measurements reflecting historical imperial practices in British maritime , while calculations for cargo capacity now use metric tonnes as of 2025. In and sectors, it appears in some longstanding contracts and specifications predating full , ensuring compatibility with older equipment and documentation. Contemporary applications include rail freight operations, such as aggregate transport, where wagon capacities are often rated around 60 tonnes—equivalent to approximately 59 long tons—allowing for mixed-unit referencing in legacy systems. Usage of the long ton has significantly declined since the metrication efforts, driven by directives promoting SI units, though it persists in nautical and specialized engineering contexts influenced by international shipping standards as of 2025.

United States Applications

In the United States, the long ton holds non-standard status and is rarely employed, as federal standards and customary practice default to the short ton of 2,000 pounds for most measurements of mass. The Metric Conversion Act of 1975 designated the metric system as preferred for trade and commerce but preserved the use of customary units without mandating a shift, reinforcing the short ton's dominance. The short ton, equivalent to approximately 907 kilograms, remains the primary unit for tonnage in American contexts. Historically, the long ton appeared in 19th-century American international trade involving Britain, particularly in contexts like shipping and exchanges where British conventions influenced documentation. Its presence reflected the era's transatlantic economic ties before the solidified as the U.S. norm. Contemporary niche applications persist in specialized fields, such as the U.S. Navy's measurement of ship displacement, where vessels like maritime prepositioning ships are rated in long tons (e.g., 55,123 long tons full load). Similarly, some references, especially those drawing on British-influenced designs, incorporate the long ton alongside other units for consistency in international collaborations. For imports, U.S. Customs and Border Protection mandates reporting in equivalents, requiring adjustments and conversions from long tons in for baled commodities or bulk goods to ensure compliance with domestic standards. This practice underscores the long ton's marginal role, limited to scenarios demanding alignment with legacy imperial systems.

International and Specialized Contexts

In international maritime practices, —a measure of cargo-carrying capacity—is expressed in metric tonnes globally under the International Maritime Organization's 1969 Convention on Tonnage Measurement of Ships, which establishes a universal volume-based system for gross and ; while some national registries accommodate imperial tons for legacy reporting as of 2025, British-flagged vessels use metric tonnes for DWT. In scientific applications, particularly and , the long ton is employed to quantify ship displacement, representing the weight of water displaced by a vessel's hull in long tons of 2,240 pounds each, facilitating calculations of and stability for research and survey ships. This unit persists in technical literature and design ratios, where displacement in long tons multiplied by 35 cubic feet per long ton yields the submerged volume in , aiding hydrodynamic analyses essential to oceanographic expeditions. The long ton continues in specialized trade sectors within Commonwealth nations; historically, Australian iron ore mining referenced "iron units" per long ton of ore in the early 2000s, but as of 2025, pricing is standardized in US dollars per dry metric tonne (e.g., 62% Fe benchmark) despite predominant metric usage. Globally, the long ton is gradually phasing out in bulk cargo contracts amid metric harmonization efforts promoted by the World Trade Organization, with international shipping now predominantly using metric tonnes; however, it endures in a small number of legacy or niche agreements as of 2025, reflecting slower transitions in specialized trades.

Comparisons with Other Mass Units

Versus Short Ton

The long ton is defined as 2,240 avoirdupois pounds, making it 240 pounds heavier than the of 2,000 avoirdupois pounds and approximately 12% greater in mass. This distinction arises from differing definitions of the : the equals 20 short hundredweights of 100 pounds each, while the long ton equals 20 long hundredweights of 112 pounds each. The emerged in 19th-century American commerce, where the 100-pound was adopted for simplicity in trade and calculations, diverging from earlier English practices. In contrast, the stems from the British imperial established by the Weights and Measures Act of 1824, which standardized the 112-pound for consistency in maritime and commercial applications across the . These variations carry significant implications for , particularly in binational US-UK contracts, where failure to specify the ton type can result in discrepancies of 240 pounds per ton, potentially leading to over- or under-shipment errors and financial disputes. Usage patterns reflect historical legacies: the short ton predominates in the United States for most commercial and industrial purposes, whereas the long ton was standard in the and territories of the former , though many have since transitioned to metric equivalents. A third option, the metric of 1,000 kilograms, approximates the long ton's mass but follows SI conventions.

Versus Metric Tonne

The long ton, equivalent to 2,240 pounds or 1,016 kilograms, exceeds the by 16 kilograms, rendering it approximately 1.6% heavier. The , defined as exactly 1,000 kilograms or 10610^6 grams, serves as a coherent derived unit within the (SI), which emphasizes decimal-based coherence for scientific and commercial applications. Its widespread standardization traces to the of 1875, an international treaty signed by 17 nations that established the International Bureau of Weights and Measures (BIPM) to ensure uniform metric practices globally. In opposition, the long ton derives from the non-decimal system of the , lacking the decimal alignment that facilitates metric computations. Global trade predominantly employs the metric tonne, as reflected in international standards and statistics. This dominance, supported by organizations like the United Nations Conference on Trade and Development (UNCTAD), minimizes conversion errors and streamlines transactions in metric-aligned markets, while the long ton imposes additional overhead in sectors interfacing with imperial legacies. In practical terms, particularly within shipping, the metric tonne enables efficient decimal-based load planning and under international conventions, enhancing across borders. The long ton persists in select cargo classification and equipment contexts, such as crane capacities calibrated to imperial scales, to preserve compatibility with historical infrastructure.

References

  1. https://www.eia.gov/tools/glossary/index.php?id=l
  2. https://www.ams.usda.gov/sites/default/files/media/GTRGlossaryofTerms.pdf
  3. https://www.sizes.com/units/ton.htm
  4. https://www.nist.gov/document/2023-nist-handbook-44-appendix-b-0
  5. https://www.govinfo.gov/content/pkg/GOVPUB-C13-466e59bf3a20481aafb33f24ea0aafcd/pdf/GOVPUB-C13-466e59bf3a20481aafb33f24ea0aafcd.pdf
  6. https://www.legislation.gov.uk/ukpga/1985/72
  7. https://www.legislation.gov.uk/ukpga/1985/72/schedule/1/part/VI
  8. https://www.checkyourmath.com/convert/weight_mass/long_ton.php
  9. https://www.buske.com/what-is/long-ton
  10. https://www.britannica.com/science/long-ton
  11. https://www.etymonline.com/word/ton
  12. https://www.britannica.com/topic/Imperial-unit
  13. https://www.nottingham.ac.uk/manuscriptsandspecialcollections/researchguidance/weightsandmeasures/weights.aspx
  14. https://physics.info/system-english/
  15. https://conversion.org/mass/pound-avoirdupois/kilogram
  16. https://metricviews.uk/2013/06/15/forgotten-british-and-irish-units/
  17. https://www.inchcalculator.com/convert/long-ton-to-metric-ton/
  18. https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors/nist-guide-si-appendix-b8
  19. https://www.census.gov/foreign-trade/guide/sec4.html
  20. https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors
  21. https://www.legislation.gov.uk/uksi/1995/1804/made
  22. https://www.gov.uk/government/consultations/choice-on-units-of-measurement-markings-and-sales/outcome/choice-on-units-of-measurement-guidance-on-markings-and-sales
  23. https://www.gov.uk/government/statistics/shipping-fleet-statistics-2024/shipping-fleet-statistics-2024-notes-and-definitions
  24. https://www.steamshipmutual.com/publications/articles/tonnage
  25. https://www.odfjelltechnology.com/activity/tonne-vs-ton-when-specifying-handling-equipment-capacities-weights/
  26. https://uk.vtg.com/products-and-services/fleet
  27. https://ukma.org.uk/what-is-metric/uk-progress/uk-metric-timeline/
  28. https://www.nist.gov/document/nist-hb-44-2024-appendix-c-general-tables-units-measurement
  29. https://usma.org/laws-and-bills/metric-conversion-act-of-1975
  30. https://www.britannica.com/science/ton
  31. https://www.navy.mil/Resources/Fact-Files/Display-FactFiles/Article/2223033/maritime-prepositioning-ships-t-ak-t-akr-and-t-aot/
  32. https://eaglepubs.erau.edu/introductiontoaerospaceflightvehicles/chapter/units-conversion-factors/
  33. https://www.imo.org/en/About/Conventions/Pages/International-Convention-on-Tonnage-Measurement-of-Ships.aspx
  34. https://www.ericwsponberg.com/wp-content/uploads/2021/09/THE-DESIGN-RATIOS.pdf
  35. https://tradingeconomics.com/commodity/iron-ore
  36. https://www.blue-growth.org/Climate_Warming_Action_Plans/Cargo_Container_Ships_Zero_Carbon_Emissions_Shipping/DWT_Deadweight_Tonnage_Tonnes_Ships_Versus_Displacement.htm
  37. https://www.wto.org/english/res_e/booksp_e/wtr23_e/wtr23_e.pdf
  38. https://www.govinfo.gov/content/pkg/GOVPUB-C13-2aca3b6352009e0772f04a41c2011d3c/pdf/GOVPUB-C13-2aca3b6352009e0772f04a41c2011d3c.pdf
  39. https://www.asseteng.com.au/blog/whats-difference-ton-tonne-one-heavier/
  40. https://science.howstuffworks.com/tonnes-vs-tons.htm
  41. https://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication1038.pdf
  42. https://www.bipm.org/en/metre-convention
  43. https://unctad.org/system/files/official-document/tdstat47_en.pdf
  44. https://www.edtengineers.com/blog-post/demystifying-measurements-or-which-ton-are-you-talking-about
  45. https://www.metric-conversions.org/weight/long-tons-to-short-tons.htm
Add your contribution
Related Hubs
User Avatar
No comments yet.