A point size explanation, gleaned from "RSD99"'s posting.
- The PostScript point: exactly 72 to the inch. [When the PostScript page description language was being designed by Adobe Systems (Jim Warnock and Charles Geschke), the PostScript point was defined as being exactly 72 points to the inch. Warnock and Geschke had an extensive knowledge of real-world printing, and of computerizing that process. They apparently took the position that 1/72.27000072 was ridiculous and overly computationally intensive, and decided to use 1/72 for the value of the point.] In other words:
This is the point system used by nearly all software nowadays.
- 1/72 inch
- or 0.013888888888 inches (the "8" is an endlessly repeating decimal)
- or 0.352777777777 millimeters (the "7" is an endlessly repeating decimal)
- The "American Printer's Point": proposed in 1886, it is roughly 72.27000072 to the inch. [The traditional American printer's point was defined by the American Typefounders Association in 1886. This convention was used by printers in the United States and England, and is still in use by those printers who use cast metal type. It is sometimes referred to as the "Anglo-Saxon point." The value of 0.013837 inches is from the NIST Handbook 44, Appendix C.]
- 1/72.27000072of an inch
- or 0.013837 inches
- or 0.3514598 millimeters
- The Didot point (of the 18th century ... roughly 1770): roughly 67.55818249 to the inch [Usually written xx ptD, the Didot point was originally defined in 1770 as 1/72th of the French Royal Inch. This French Royal Inch was 27.07 mm long, which was slightly longer than the English inch of the time. The Didot point is commonly used by continental European printers and typesetters. Since it is visibly slightly larger than the commonly used Anglo-Saxon "printer's point," the Didot point is sometimes called the 'fat point.']
- 1/67.55818249 of an inch (roughly)
- or 0.014802056 inches
- or 0.3759722222 millimeters
- There are also historical "point" measurements by Fournier (1737) and Truchet (1695), and one by the French printer Imprimerie Nationale.
- Points (l'Imprimerie nationale): The l'Imprimerie nationale point was defined as 0.4 millimeter. It is now obsolete.
- Points (Truchet, 1694): The Truchet point is defined as 1/12th of 1/12th of the French Royal foot. It was never accepted by the printing industry, and is now obsolete.
- Points (Fournier, 1737): In 1737 Pierre Fournier formulated the first definition of the point as being 1/12th of the French "Cicero" type size. The "Cicero" was then 0.1648 inches, so the Fournier point was approximately 0.013733 inches. This definition was originally presented in his booklet "Tables des Proportions qu'il faut observer entre les caractères."
Google search page
Type measurements ⦿
Modern style [Bodoni, Didot, Walbaum, Thorowgood, Computer Modern, etc.] ⦿