Picas

The pica is a typographic unit of measure corresponding to approximately  1/6 of an inch, or  1/72 of a foot. One pica is further divided into 12 points.

To date, in printing three pica measures are used:

• The French pica of 12 Didot points (also called cicéro) generally is: 12 × 0.376 = 4.512 mm (0.1776 in).
• The American pica of 0.016044 inches (0.4075 mm). It was established by the United States Type Founders' Association in 1886. In TeX one pica may be defined as  12/72.27 of an inch.
• The contemporary computer pica is exactly  1/6 of a 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 5.5 picas.

CSS defined by the World Wide Web Consortium use pc as the abbreviation for pica ( 1/6 of an inch), and pt for point ( 1/72 of an inch).

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, a 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).

Picas
Symbol/abbreviation: p
Unit of: LENGTH
LENGTH's base unit: meters (SI Unit)
In relation to the base unit (meters), 1 Picas = 0.00423333333 meters.