|Unit system||typographic unit|
|1 point in ...||... is equal to ...|
|typographic units||1/ picas|
|imperial/US units||1/ in|
|metric (SI) units||0.3528 mm|
In typography, the point is the smallest unit of measure. It is used for measuring font size, leading, and other items on a printed page. The size of the point has varied throughout the history of printing. Since the 18th century, the point's size has varied from 0.18 to 0.4 millimeters. Following the advent of desktop publishing in the 1980s and 1990s, digital printing has largely supplanted the letterpress printing and has established the DTP point (desktop publishing point) as the de facto standard. The DTP point is defined as 1⁄72 of an international inch (about 0.353 mm) and, as with earlier American point sizes, is considered to be 1⁄12 of a pica.
In metal type, the point size of the font described the height of the metal body on which the typeface's characters were cast. In digital type, letters of a font are designed around an imaginary space called an em square. When a point size of a font is specified, the font is scaled so that its em square has a side length of that particular length in points. Although the letters of a font usually fit within the font's em square, there is not necessarily any size relationship between the two, so the point size does not necessarily correspond to any measurement of the size of the letters on the printed page.
A measurement in points can be represented in three different ways. For example, 14 points (1 pica plus 2 points) can be written:
- 1P̸2p (12 points would be just "1P̸")—traditional style
- 1p2 (12 points would be just "1p")—format for desktop
- 14pt (12 points would be "12pt" or "1pc" since it is the same as 1 pica)—format used by Cascading Style Sheets defined by the World Wide Web Consortium
There have been many definitions of a “point” since the advent of typography. Traditional continental European points at about 375 µm are usually a bit larger than English points at around 350 µm.
The Truchet point, the first modern typographic point, was 1/ of a French inch or 1/ of the royal foot. It was invented by the French clergyman Sébastien Truchet. During the metrication of France amid its revolution, a 1799 law declared the meter to be exactly 443.296 French lines long. At 9000 lines or 16 inches per foot, this established a length to the royal foot of 9000/ or ca. 325 mm, which made the Truchet point equal to 62515/mm or about µm, although it has also been cited as exactly 188 187.986 µm.
The Fournier point established by Pierre Simon Fournier was about 11/ French inches or (by 1799) 345 µm. This is very close to the present international point, but Fournier's point did not achieve lasting popularity despite being revived by the Monotype Corporation in 1927. It became standard in Belgium.
Approximations were subsequently employed, largely owing to the Didot point's unwieldy conversion to metric units. (The divisor of its conversion ratio has the prime factorization of 3×7×1979.) Values included Hermann Berthold's 376 µm point and Jan Tschichold's µm (266 points to 100 375.94 mm). Due to the definition in TeX of 1157 dd = 1238 pt, the slightly larger µm became a common value. 376.065
TeX also supports a new Didot point (nd) at 3/mm or 375 µm, and cites a 1978 redefinition for it. The French National Print Office adopted a point of 2/mm or 400 µm exactly and continues to use this measurement today. Japanese and German standardization bodies instead opted for a metric typographic base measure of exactly 1/mm or 250 µm. It is called キゥ kyu in Japanese after the English pronunciation of its letter symbol 'q' from quarter millimetre. Due to demand by Japanese typesetters, CSS adopted q in 2015.
The Didot point has been mostly replaced by the DTP point in Europe and throughout the world.
A typographic or printer's foot contains 72 picas or 864 points. The Metric Act of 1866 established a legal ratio of 1200 : 3937 between the foot and the meter. This is 0.0002% more than 304.8 mm, the length of the international foot established by the 1959 International Yard and Pound Agreement.
The Hawks point was established by Nelson Hawks in 1879, based on a printer's foot reduced by 0.375% from the standard foot of his time. It had a value of 837 in (about 0.01346 mm). A variant was proposed to be exactly 83 0.351 picas or 996 points in 350 mm (ca. 405622 mm/pt), giving it a value around 0.351848867 in. 0.013
The Johnson point was established by Lawrence Johnson in the mid-1800s based on a printer's foot 249⁄250 as large as the standard foot (11.952 inches or 0.996 foot). It thus had a value of 0.01383 inch. The 15th meeting of the Type Founders Association of the United States (ATA) approved the "Johnson pica" as its official standard in 1886, hence the alias ATA point. Following the 1959 standardization of the foot, this meant the American printer's foot was 303.5808 mm exactly and its point became 351.36 µm.
This size was approximated by Donald Knuth for the default unit of his TeX computer typesetting system and is thus sometimes known as the TeX point, which is 351.45980 µm or exactly 1⁄72.27 of the modern inch, and exactly 800⁄803 of the PostScript point (bp in TeX).
Like the French Didot point, the traditional American printer's point was largely replaced by the DTP point system.
Desktop publishing point
The desktop publishing point (DTP point) or PostScript point is defined as 1⁄72 or 0.0138 of the international inch, making it equivalent to 352.7 µm. Twelve points make up a pica, and six picas make an inch. A separate typographic or printer's foot is not needed anymore.
This specification was developed by John Warnock and Charles Geschke when they created Adobe PostScript. It was adopted by Apple Computer as the standard for the display resolution of the original Macintosh desktop computer and the print resolution for the LaserWriter printer.
Fonts originally consisted of a set of moveable type letterpunches purchased from a type foundry. As early as 1600, the sizes of these types—their "bodies"—acquired traditional names in English, French, German, and Dutch, usually from their principal early uses. These names were used relative to the others and their exact length would vary over time, from country to country, and from foundry to foundry. For example, "agate" and "ruby" used to be a single size "agate ruby" of about 5 points; metal type known as "agate" later ranged from 5 to 5.8 points. The sizes were gradually standardized as described above. Modern Chinese typography uses the following names in general preference to stating the number of points. In ambiguous contexts, the word hào (t 號, s 号, lit. "number") is added to the end of the size name to clarify the meaning.
Note that the Chinese font sizes use American points; the Continental systems traditionally used the Fournier or Didot points. The Fournier points, being smaller than Didot's, were associated with the names of the Didot type closest in size rather than identical in number of points.
|Point||American system||Continental system||Chinese system|
|1 1/||German||Achtelcicero||Achtste cicero|
|2||Saxon|| Non Plus Ultra|
| Non plus ultra
|2 1/||Norse||Microscopique||Microscopique|| Microscoop
|3 1/|| Ruby|
|6 1/||Minionette||Emerald||Insertio||Insertio||小六||Xiǎoliù||"Little Six"|
|10||Long Primer||Philosophie|| Korpus|
|11||Small Pica||Cicéro|| Rheinländer|
|14||English||Gros-texte||Mittel|| Grote cicero
|18||Great Primer||Gros-romain||1 1/ Cicero|| Paragon
|22||Double Small Pica||Gros-parangon||二||Èr||"Two"|
|24||Double Pica||Palestine||Doppelcicero|| Dubbele cicero
|28||Double English||Petit-canon||Doppelmittel||Dubbele mediaan|
|32||Double Columbian|| Kleine Kanon|
|36||Double Great Primer||Trismégiste|| Kanon|
|40||Double Paragon|| Doppeltext|
|42||Seven-line Nonpareil||Große Kanon||Grote Kanon||初||Chū||"Initial"|
|48|| Four-line Pica
|Canon||Gros-canon||Kleine Missal|| Konkordanz
|60||Five-line pica||Große Missal||Sabon|
|66||Große Sabon||Grote sabon|
|72|| Six-line pica|
|84||Seven-line pica|| Siebencicero|
|96||Eight-line pica||Grosse-nonpareille|| Achtcicero|
|100||Moyenne de fonte|
|108||Nine-line pica||Imperial||9 cicero|
- Phinney, Thomas (16 August 2012). "Point Size and the Em Square: Not What People Think". Phinney on Fonts. Retrieved 24 February 2015.
- "Chapter 15: Fonts". Cascading Style Sheets Level 2 Revision 1 (CSS 2.1) Specification. 17 December 2014. § 15.8. Retrieved 24 February 2015.
- JIS X 4052:2000, JIS Z 8125:2004
- as an unnamed module first in DIN 16507-2:1984 and still in DIN 16507-2:1999
- JIS Z 8305
- pdftex source code l. 10443 ff.
- "What are the various units (ex, em, in, pt, bp, dd, pc) expressed in mm?". Stacke Exchange.
- David Baron (2009-03-09). "Remove internal support for units that were never in CSS (feet, miles, meters, kilometers, didots, ciceros)". Mozilla.org.
- "AH Formatter: XSL/CSS Extensions". p. Extended Units.
- Public Law 39-183.
- pdftex source code l. 13773 ff.
- Tucker, H. A. (1988). "Desktop Publishing". In Ruiter, Maurice M. de. Advances in Computer Graphics III. Springer. p. 296. ISBN 3-540-18788-X.
- Spring, Michael B. (1991). Electronic printing and publishing: the document processing revolution. CRC Press. p. 46. ISBN 0-8247-8544-4.
- Southward, John (1888), "Typography", Encyclopædia Britannica, 9th ed., Vol. XXIII, New York: Charles Scribner's Sons, p. 698.
- Romano, Frank (Summer 2009). "The History of the Typographic Point" (PDF). APHA Newsletter (171): 3–4.
- "Type", Sizes.com, Santa Monica: Sizes Inc., 2004.
- Pasko, Wesley Washington, ed. (1894), American Dictionary of Printing and Bookmaking, Containing a History of These Arts in Europe and America, with Definitions of Technical Terms and Biographical Sketches, New York: Howard Lockwood & Co., p. 522.
- Pasko (1894), p. 215.
- Bauer, Friedrich (1929), Die Normung der Buchdrucklettern: Schrifthöhe, Schriftkegel, und Schriftlinie in ihrer geschichtlichen Entwichlung, Leipzig: Deutscher Buchgewerbeverein, p. 64. (German)
- The existence of such small bodies was only notional in the age of metal type.
- Pasko (1894), p. 18.
- Bauer (1934).
- De Vinne (1900), p. 68.
- De Vinne, Theodore Low (1900), The Practice of Typography: A Treatise on the Processes of Type-Making, the Point System, the Names, Sizes, Styles, and Prices of Plain Printing Types, New York: The Century Co., p. 68.
- "minikin, n.¹ and adj.¹", Oxford English Dictionary, 3rd ed., Oxford: Oxford University Press, 2002.
- Note that the American name for 3-point type was initially "Brilliant" and the English name was initially "Excelsior". The American "Excelsior", meanwhile, was originally 4-point type. The situation subsequently changed.
- "excelsior, n."'", Oxford English Dictionary, 1st ed., Oxford: Oxford University Press, 1894.
- Pasko (1894), p. 70.
- "ruby, n.¹", Oxford English Dictionary, 3rd ed., Oxford: Oxford University Press, 2011
- Pasko (1894), p. 11.
- "minionette, n.", Oxford English Dictionary, 3rd ed., Oxford: Oxford University Press, 2002.
- Pronounced "burjoyce".
- Pasko (1894), p. 65.
- Pasko (1894), p. 229.
- The French gros-texte referred indifferently to type sizes between 14 and 16 points.
- Pasko (1894), p. 172.
- Pasko (1894), p. 238.
- von Bauer, Friedrich (1934), Handbuch für Schriftsetzer, Frankfurt: Verlag von Klimsch & Co.. (German)
- Staeck (1980).
- The German Große Kanon referred indifferently to 40- or 42-point type.
- The French gros-canon referred indifferently to type sizes of 44 or 48 points.
- Pasko (1894), p. 79.
- Pasko (1894), p. 213.
- Staeck, Erich; et al. (1980), Rechenbuch für die Druckindustrie, Itzehoe: Verlag Beruf und Schule, ISBN 3-88013-155-4. (German)