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Line length
View on WikipediaIn typography, line length is the width of a block of typeset text, usually measured in units of length like inches or points or in characters per line (in which case it is a measure). A block of text or paragraph has a maximum line length that fits a determined design. If the lines are too short then the text becomes disjointed; if they are too long, the content loses rhythm as the reader searches for the start of each line.
Line length is determined by typographic parameters based on a formal grid and template with several goals in mind: balance and function for fit and readability with a sensitivity to aesthetic style in typography. Typographers adjust line length to aid legibility or copy fit. Text can be flush left and ragged right, flush right and ragged left, or justified where all lines are of equal length. In a ragged right setting, line lengths vary to create a ragged right edge. Sometimes this can be visually satisfying. For justified and ragged right settings typographers can adjust line length to avoid unwanted hyphens, rivers of white space, and orphaned words/characters at the end of lines (e.g., "The", "I", "He", "We").
Printed text
[edit]Traditional line length research, limited to print-based text, gave a variety of results, but generally for printed text it is widely accepted that line lengths fall between 45 and 75 characters per line (cpl), though the ideal is 66 cpl (including letters and spaces).[1] For conventional books line lengths tend to be 30 times the size of the type, but between 20 and 40 times is considered acceptable (i.e., 30 × 10pt font = 300 pt line).[1] Early studies considered line lengths of 59–97 mm (about 57 cpl) optimum for 10-point font.[2] For printed works with multiple columns, 40–50 cpl is often better.[1] For justified, English-language text the minimum number of characters per line is 40; anything less than 38–40 characters often results in splotches of white spaces (or rivers) or too many hyphenations in the block of text.[1] Longer lines (85–90 cpl) may be acceptable for discontinuous text such as in bibliographies or footnotes, but for continuous text lines with more than 80 characters may be too long. Short text, such as ragged marginal notes, may be as little as 12–15 characters per line.[1] Studies have shown that short lines are often preferred over long lines by study participants, likely because they feel more at ease with format, which contradicts research suggesting longer lines are best for quick reading.[3] Punctuation should preferably hang outside the measure.[4] Generally, if the measure is wide, the leading of a text should be increased—if the measure is short, it can safely be decreased. Reverse text, i.e. white text on black, also requires more leading.[5][6]
The experience of the reader can also be considered as a factor when determining the count of characters within text lines. For novice readers, text lines should contain between 34 and 60 characters, 45 being the optimal number. Texts for expert readers could contain between 45 and 80 characters, with an optimal count of 60 characters.[7]
Electronic text
[edit]Screen reading poses additional challenges, making the adoption of traditional line length research to the digital format problematic.[8] Unlike printed text, writing for digital media must accommodate factors such as glare, flicker, and scrolling/paging.[9]
The measure is the number of characters per line in a column of text. Using CSS to set the width of a box to 66ch fixes the measure to about 66 characters per line regardless of the text size as the ch unit is defined as the width of the glyph 0 (zero, the Unicode character U+0030) in the element's font.[10] For user agents that do not support the ch unit a value of 33em can be used as, on average, one character takes up 0.5 of a typographic em.[5]
Legibility research specific to digital text has shown that, like with printed text, line length can affect reading speed. If lines are too long it is difficult for the reader to quickly return to the start of the next line (saccade), whereas if lines are too short more scrolling or paging will be required.[11]
Researchers have suggested that longer lines are better for quick scanning, while shorter lines are better for accuracy.[3] Longer lines would then be better suited for cases when the information will likely be scanned, while shorter lines would be appropriate when the information is meant to be read thoroughly.[3] One proposal advanced that, in order for on-screen text to have the best compromise between reading speed and comprehension, about 55 cpl should be used.[11] On the other hand, there have been studies indicating that digital text at 100 cpl can be read faster than text with lines of 25 characters, while retaining the same level of comprehension.[8]
Subjective factors also play a role in line length selection for digital text. One study has found that CPL had only small effects on readability, including factors of speed and comprehension; but when asked for preferences, 60% of respondents indicated a preference for either the shortest (35 CPL) or longest (95 CPL) lines used in the study. At the same time, 100% of respondents selected either one of these quantities as being the least desirable.[12]
Calculation methods
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There are a few methods to calculate line length to fit the intended average count of characters that such lines should contain based on the factors listed above. Most, if not all, of these methods use the length of the lowercase alphabet (LCA) as a reference for its calculation.[13] The lowercase alphabet (a measurement of the array of characters of the hegemonic roman alphabet from a to z in typographic points) was sometimes included in type specimen booklets. If not available, the first step to calculate the line length for all these methods is the measurement of the LCA at the size that will be ultimately used.
The first of these methods consists of an adjacency matrix that positions the LCA in points on the x axis and the line length in picas on the y axis. The matrix is used by locating the number closest to the previously calculated LCA on the left column of the matrix and then scanning across the columns the number of characters that one would like to set in the text line. Once the number is located, the top row of the selected column will indicate the ideal line length.[13]
The second method consists of a formula that uses the LCA as a unit in a rule of three calculation.[7] Given that the lowercase alphabet has 26 characters, multiplying LCA by 1.75 roughly yields the optimal number of characters for novice readers (26 × 1.75 = 45.5 [≈ 45]). Multiplying the optimal number of character by 0.75 yields the minimum number of characters for novice readers (45.5 × 0.75 = 34.125 [≈ 34]), while multiplying this same number by 1.5 roughly yields the maximum number of characters for novice readers (45.5 × 1.5 = 68.25 [≈ 60]).
The third known method is also a formula (LCA’ × Cρ[S] = Ll) that consists of multiplying a modified version of LCA (the lowercase alphabet plus a space character [LCA’]) by the desired number of characters (Cρ) multiplied by a constant of 0.0345 (S).[14]
References
[edit]- ^ a b c d e Bringhurst, R. (1992). Horizontal Motion. The Elements of Typographic Style, pp 25-36. Point Roberts, WA: Hartley & Marks.
- ^ Tinker, M. A., & Paterson, D. G. (1929). Studies of typographical factors influencing speed of reading. III. Length of line. Journal of Applied Psychology, 13(3), 205-219.
- ^ a b c Ling, J., & Van Schaik, P. (2006). The influence of font type and line length on visual search and information retrieval in web pages. International Journal of Human-Computer Studies, 64(5), 395-404.
- ^ "10 Great Tips For Improving Your Web Typography - SpyreStudios". 14 May 2010. Archived from the original on 8 February 2017. Retrieved 6 February 2017.
- ^ a b Rutter, Richard. "Choose a comfortable measure - The Elements of Typographic Style Applied to the Web". Retrieved 8 August 2022.
- ^ Boulton, Mark (13 April 2005). "Five simple steps to better typography".
- ^ a b Buen Unna, Jorge de. (2014). Manual de diseño editorial (4a ed., corr. y aum ed.). Somonte-Cenero, Gijón: Ediciones Trea. ISBN 9788497047623. OCLC 880551642.
- ^ a b Dyson, M. C., & Kipping, G. J. (1998). The Effects of Line Length and Method of Movement on Patterns of Reading from Screen. Visible Language, 32(2), 150-181.
- ^ Nanavati, A. A., & Bias, R. G. (2005). Optimal line length in reading - a literature review. Visible Language, 29(2), 121-145.
- ^ "<length> CSS data type". Retrieved 8 August 2022.
- ^ a b Dyson, M. C., & Haselgrove, M. (2001). The influence of reading speed and line length on the effectiveness of reading from screen. International Journal of Human-Computer Studies, 54(4), 585-612.
- ^ Shaikh, A. Dawn (July 2005). "The Effects of Line Length on Reading Online News". Usability News. 7 (2). Archived from the original on June 19, 2015.
- ^ a b Robert., Bringhurst (2012). The elements of typographic style (4th ed. (version 4.0) ed.). Seattle, WA: Hartley & Marks. ISBN 9780881792119. OCLC 808199932.
- ^ Peña, Ernesto (2016). "Calculating line length: an arithmetic approach". Visible Language. 50 (1): 112–125. Archived from the original on 2017-09-05. Retrieved 2019-01-04.
Line length
View on GrokipediaFundamentals
Definition
In typography, line length, also known as measure, refers to the width of a block of typeset text, defined as the horizontal distance from the left margin to the right margin of the text block.[1][7] This dimension is typically quantified in terms of the average number of characters per line (including spaces), the number of words, or physical units such as picas (a traditional print measurement where 1 pica equals 12 points or approximately 1/6 inch) or em spaces (a relative unit equal to the current font size).[8][9][10] Several key parameters influence the perceived line length beyond its raw measurement, including font size, which determines how many characters fit within a given width; leading (the vertical space between lines), which can alter the overall density and visual flow of the text block; and justification (the alignment of text, such as left-aligned, centered, or fully justified), which affects spacing distribution and the evenness of line endings.[11][12][13] These factors collectively shape how the line length is experienced visually, impacting the text's rhythm and legibility without changing the margins themselves.[14] Basic examples of line length variation appear in print layouts, such as single-column newspaper formats that may span broader widths for headlines or editorials, contrasted with multi-column magazine layouts that divide text into narrower measures to accommodate dense content across pages.[15][16] This approach ensures the line length suits the medium's spatial constraints and reading context.[17]Importance for Readability
Line length plays a crucial role in readability due to the psychological processes underlying text comprehension, particularly how the eyes process written information. Early research by E.B. Huey in the early 20th century established the foundational understanding of eye movements during reading through pioneering eye-tracking experiments, revealing that readers do not perceive text in a smooth sweep but through discrete pauses and jumps.[18] These findings highlighted that inefficient visual processing from poorly structured text increases mental effort and reduces comprehension efficiency.[19] During reading, the eyes alternate between fixations—brief pauses lasting about 200-250 milliseconds where visual information is extracted—and saccades, rapid jumps that reposition the gaze, typically spanning 7-9 character spaces forward in alphabetic languages like English.[20] The perceptual span, or visual span, the amount of text recognized per fixation, is asymmetric and limited to approximately 3-4 characters to the left and 14-15 characters to the right of the fixation point for skilled readers of English, making optimal line lengths essential to minimize unnecessary saccades and regressions that disrupt flow.[21] Suboptimal line lengths force more frequent or longer saccades, leading to greater eye strain and slower reading speeds as the brain compensates for visual inefficiency.[22] In terms of readability metrics, excessive line lengths in justified text often produce "rivers"—vertical white spaces formed by uneven word spacing—that break the page's visual texture and hinder smooth tracking across lines, particularly impairing quick scanning tasks.[23] Conversely, overly short lines exacerbate hyphenation issues, where frequent breaks create a "picket fence" effect of aligned hyphens along the margin, causing visual disruption and increased cognitive effort to parse fragmented phrasing.[24] These artifacts elevate extraneous cognitive load by diverting attention from content to navigational challenges, thereby overloading working memory and reducing comprehension. Balanced line lengths minimize these loads, enhancing overall text processing.[20]Printed Text
Historical Development
The historical development of line length standards in print media originated in the mid-15th century with the advent of movable-type printing, which largely emulated the layouts of medieval manuscripts to ensure familiarity and readability for early readers. Johannes Gutenberg's Bible, printed circa 1455, featured double-column pages with approximately 40-50 characters per line, a length influenced by manuscript traditions where scribes typically limited lines to 4-9 words to facilitate copying and reduce eye strain during prolonged reading sessions.[25][26] This approach prioritized compact, justified text blocks that mirrored the narrow columns common in codices, balancing content density with legibility on vellum or early paper substrates. By the 19th century, as printing scaled for mass production, standardization efforts emerged through the works of influential printers like Theodore Low De Vinne, whose treatises on typography emphasized em-based measures for consistent line widths. In his 1902 volume The Practice of Typography: Correct Composition, De Vinne recommended measures such as 8 ems of 6-point type for one broad quotation and 12 ems for two narrow quotations in side-notes, while extracts were often indented 1 em on each side to maintain visual hierarchy.[27] These recommendations reflected the era's shift toward justified ragged-right margins in some contexts, allowing printers to adapt line lengths to publication formats like pocket editions without excessive hyphenation, thereby influencing typesetting norms across American and European presses. The 20th century brought further refinements with the rise of hot-metal typesetting technologies, such as Linotype (introduced in 1886), which automated justification and enabled precise control over line lengths in high-volume production. Seminal readability studies by psychologists Miles A. Tinker and Donald G. Paterson, conducted in collaboration with printing industry initiatives, provided empirical foundations for standards; their 1929 experiments using 10-point type on white paper identified 3-4 inch lines (roughly 45-60 characters) as optimal for speed and comprehension, while their 1940 eye-movement research confirmed that lines of 45-75 characters minimized regressions without sacrificing efficiency.[28] These findings, disseminated through reports influencing the Printing Industry Research Association and similar bodies, solidified 45-75 characters as a benchmark for book and newspaper composition, adapting historical practices to industrial demands.Optimal Guidelines
For body text in printed materials, evidence-based guidelines recommend line lengths of 45 to 75 characters per line, including spaces, to optimize readability by accommodating efficient eye movements without excessive saccades or returns.[29] This range corresponds to approximately 2 to 3 ems (or "alphas," the width of the lowercase alphabet in the given typeface), a standard measure in typography that balances visual comfort and comprehension.[1] For footnotes, which often use smaller type sizes, narrower lines are advised to prevent fatigue during brief, supplementary reading.[30] Format-specific recommendations refine these standards based on medium and layout. In books, a line length of about 60 characters—equivalent to roughly 19 picas for 10-point type with 2-point leading—has been shown to maximize reading speed and accuracy in continuous prose.[30] Newspapers typically employ shorter measures: single-column formats around 40 characters to suit rapid scanning, while multi-column layouts use 25 to 30 characters per line to fit dense information across narrow widths without sacrificing legibility.[31] For advertisements, line lengths vary by audience and purpose, often ranging from 40 to 70 characters to align with persuasive, skimmable content, though testing for specific demographics is emphasized over rigid rules.[2] Several factors influence these optimal lengths, drawing from legibility tests conducted in the 1920s and beyond. Serif typefaces are generally preferred over sans-serif for body text in print, as supported by legibility studies, though differences are often minimal at standard sizes.[30] High-quality paper, such as eggshell stock with minimal show-through, improves contrast and thus effective line length tolerance, while poor newsprint can reduce legibility by diminishing brightness.[30] Adequate illumination, ideally 10 to 25 foot-candles with diffused light to avoid glare on glossy surfaces, further supports readability; suboptimal lighting (e.g., below 3 foot-candles) exacerbates issues with longer lines.[30] These insights stem from pioneering speed-of-reading experiments by Miles Tinker and Donald Paterson, who tested variations in line width, type, and conditions across hundreds of studies starting in the late 1920s.[30]Electronic Text
Display Medium Differences
Electronic displays introduce distinct challenges to line length principles originally developed for print, where higher resolutions and fixed viewing conditions allow for more consistent readability. While traditional web design assumes screens operate at 72-96 pixels per inch (PPI), modern displays often exceed 200 PPI, far lower than print's 300+ dots per inch (DPI) in most cases, resulting in less sharp text rendering that demands shorter lines to maintain clarity and reduce visual fatigue.[32][33] The emissive nature of LCD and OLED panels reduces perceived contrast in ambient light compared to print's reflective surface, as external light washes out the screen's output.[34][35] Additionally, variable viewing distances—arm's length for desktops versus closer handheld use for mobiles—alter perceived line lengths, requiring adjustments to prevent excessive eye movement.[11] Device-specific constraints further differentiate electronic line lengths from print's uniform 50-75 character optimum. Desktops, with larger viewports, accommodate wider lines up to 85 characters without severe readability loss, though 50-75 remains ideal to align with eye-tracking rhythms.[2][11] Mobiles, constrained by narrow screens and thumb-based navigation, necessitate 30-50 characters to facilitate single-handed scrolling and minimize horizontal panning.[36] E-readers, designed to emulate print with e-ink technology, support 50-70 characters, benefiting from matte surfaces that reduce glare and fixed reading postures similar to books.[2] Ergonomic factors on electronic displays amplify these differences, as foveal vision—spanning roughly 13 characters to the right of fixation—limits effective line processing on pixelated screens more than on high-resolution print.[37] Blue light emissions from LCD and OLED panels contribute to eye strain during extended reading; studies show OLED induces greater ocular surface disruption than e-ink due to higher peak intensities and flicker at low brightness.[38][39] The Web Content Accessibility Guidelines (WCAG) 2.1 address these via Success Criterion 1.4.10 (Reflow), requiring content to reflow at 400% zoom within a 320 CSS pixel width viewport, ensuring line lengths do not force horizontal scrolling and promoting accessibility across display types.[40]Adaptive Techniques
Adaptive techniques in digital interfaces dynamically adjust line length to optimize readability across varying screen sizes, user preferences, and device orientations, enhancing user experience by minimizing eye strain and improving text flow. These methods leverage web technologies and application features to ensure text remains within comfortable reading ranges, typically 50-75 characters per line, regardless of the display medium. Unlike fixed layouts in print, adaptive approaches prioritize flexibility to accommodate diverse viewing conditions. Responsive design employs CSS media queries to apply styles based on viewport dimensions, such as screen width breakpoints, allowing line lengths to scale fluidly. For instance, developers often set a maximum width of 75 characters using thech unit—where 1ch approximates the width of the "0" glyph—to constrain text containers, as in max-width: 75ch; for body text, preventing excessively long lines on wide screens.[41] Viewport units like vw (1% of viewport width) further enable proportional scaling, such as setting font sizes or margins to clamp(1rem, 2.5vw, 1.5rem) to maintain balanced line lengths as the browser window resizes.
User controls empower individuals to customize line length directly, with browsers supporting zoom and font size adjustments that trigger automatic reflow of text. E-reading applications like Amazon Kindle offer options to adjust words per line, enabling users to shorten lines on larger screens for optimal viewing.[42] In professional tools, Adobe InDesign facilitates adaptive reflow during digital exports to EPUB formats via Smart Text Reflow, which automatically adjusts text flow and line breaks when frames are resized, ensuring consistent readability in reflowable e-books.[43]
Best practices favor liquid (or fluid) layouts over fixed-width ones, as liquid designs use relative units to adapt content width to the viewport, avoiding the readability issues of overly long lines in fixed setups on high-resolution displays. Fixed layouts maintain a constant pixel width, which can result in short lines on mobile devices or excessively wide ones on desktops, whereas liquid approaches distribute text more evenly. Research from the Baymard Institute, based on large-scale usability testing, recommends targeting 50-75 characters per line generally, noting that on touch devices shorter lines reduce horizontal scrolling.[2] This aligns with broader UX guidelines emphasizing adaptive scaling to support diverse hardware, from smartphones to ultrawide monitors.[44]