A pica is a typesetting unit of measurement commonly used for measuring lines of type. One pica equals 12 points. There are 6 picas to an inch although there are actually multiple pica sizes.
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Three Measures of a PicaThe size of a point and a pica has varied over the years and often printers devised their own measures not commonly found outside their own print shop. However there are three commonly recognized, more or less standardized, pica sizes.
- French pica, which is made up of 12 Didot points, is 0.177 inch
- Traditional British and American pica, made of 12 points, which measures 0.166044 inch
- PostScript or computer pica that comes in at 0.166 of an inch. This is the most widely used pica measurement used in modern desktop publishing
Typically, pica is used for measuring the width and depth of columns and margins. Points are used to measure smaller elements on a page such as type and leading.
The letter p is used to designate picas as in 22p or 6p. With 12 points to the pica, half a pica would be 6 points written as 0p6. Seventeen (17) points would be 1p5 (1 pica = 12 pts, plus the leftover 5 pts).
Pica is also used to describe a 12 point typewriter type that prints 10 characters per inch (cpi).