Understanding a Pica

Picas are used to measure column widths and depths

Typescript metal letters
Busà Photography / Getty Images

A pica is a typesetting unit of measurement commonly used for measuring lines of type. One pica equals 12 points, and there are 6 picas to an inch. Many digital graphic designers use inches as the measurement of choice in their work, but picas and points still have plenty of followers among typographers, typesetters, and commercial printers.

Size of a Pica

The size of a point and a pica varied throughout the 18th and 19th centuries.

However, the standard used in the U.S. was established in 1886. American picas and PostScript or computer picas measure 0.166 inches. This is the pica measurement used in modern graphic design and page layout software.

What Is a Pica Used For?

Typically, picas are 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. Because picas and points are still used in most newspapers, you may need to prepare advertisements for your daily paper in picas and points.

In page layout software such as Adobe InDesign and Quark Express, the letter p designates picas when it is used with a numeral, such as in 22p or 6p. With 12 points to the pica, half a pica is 6 points written as 0p6. Seventeen point is written 1p5 (1 pica = 12 points, plus the leftover 5 points). Those same page layout programs also offer inches and other measurements (centimeters and millimeters, anyone?) for people who don't want to work in picas and points.

The conversion in software between units of measurement is a quick one. 

In CSS for the web, the pica abbreviation is pc. 

Pica Conversions

1 inch = 6p 

1/2 inch = 3p

1/4 inch = 1p6 (1 pica and 6 points)

1/8 inch = 0p9 (zero picas and 9 points)

A column of text that is 2.25 inches wide is 13p6 wide (13 picas and 6 points)

1 point = 1/72 inch

1 pica = 1/6 inch

Why Use Picas?

If you are comfortable with one measurement system, there is no urgent need to change. Graphic artists and typographers who have been around for a while have the pica and point systems drilled into them. It is as easy for them to work in picas as in inches. The same can be said for people who came up in the newspaper industry. 

Some people argue that picas are easier to use because they are a "base 12" system and are easily divided by 4, 3, 2 and 6. Some don't like to work with decimals that crop up since 1 point actually equals 0.996264 inches. 

Graphic artists who work with a variety of clients will find that some use inches and some use picas, so a basic understanding of both systems comes in handy.