A ruler showing Pica scale (on the top) and Agate scale (on the bottom)
|Unit system||typographic unit|
|1 pica in ...||... is equal to ...|
|typographic units||12 points|
|imperial/US units||1/ in|
|metric (SI) units||4.2333 mm|
To date, in printing three pica measures are used:
- The French pica of 12 Didot points (also called cicero) generally is: 12 × 0.376 = 4.512 mm (0.1776 in).
- The American pica of 0.16604 inches (4.217 mm). It was established by the United States Type Founders' Association in 1886. In TeX one pica is 12⁄72.27 of an inch.
- The contemporary computer PostScript pica is exactly 1⁄6 of an inch or 1⁄72 of a foot, i.e. 4.233 mm or 0.166 inches.
Publishing applications such as Adobe InDesign and QuarkXPress represent pica measurements with whole-number picas left of a lower-case p, followed by the points number, for example: 5p6 represents 5 picas and 6 points, or 51⁄2 picas.
The pica is also used in measuring the font capacity and is applied in the process of copyfitting. The font length is measured there by the number of characters per pica (cpp). As books are most often printed with proportional fonts, cpp of a given font is usually a fractional number. For example, an 11-point font (like Helvetica) may have 2.4 cpp, thus a 5-inch (30-pica) line of a usual octavo-sized (6×8 in) book page would contain around 72 characters (including spaces).
There have existed copyfitting tables for a number of typefaces, and typefoundries often provided the number of characters per pica for each type in their specimen catalogs. Similar tables exist as well with which one can estimate the number of characters per pica knowing the lower-case alphabet length.
The typographic pica must not be confused with the Pica font of the typewriters, which means a font where 10 typed characters make up a line one inch long.
- Legros, Lucien Alphonse; Grant, John Cameron (1916). Typographical Printing-Surfaces. London and New York: Longmann, Green, and Co. pp. 57–60.
- Hyde, Grant Milnor (1920). Newspaper Editing: A Manual for Editors, Copyreaders, and Students of Newspaper Desk Work. New York and London: D. Appleton and Company. pp. 226–227.
- "Syntax and basic data types". W3.org. Retrieved 2016-10-21.
- Pipes, Alan (2005). Production for Graphic Designers (4th ed.). Laurence King Publishing. pp. 48–49.
- Montagnes, Ian (1991). Editing and Publication: A Training Manual. p. 343.
- Newsom, Doug; Haynes, Jim (2010). Public Relations Writing: Form & Style. Cengage Learning. pp. 392–395. ISBN 1-4390-8272-3.
- Dahl, Fred (2006). Book Production Procedures for Today's Technology (2nd ed.). Inkwell Publishing Service. p. 21.
- Jackson, Hartley Everett (1942). Newspaper Typography, a Textbook for Journalism Classes. Stranford University Press. pp. 36–37.
- Clair, Kate; Busic-Snyder, Cynthia (2012). A Typographic Workbook: A Primer to History, Techniques, and Artistry. John Wiley & Sons. pp. 101–104. ISBN 978-1-118-39988-0.