Non-Designer’s Type Book, The, Second Edition

Paragraph Indents

So let’s say you are going to indent your paragraphs. Are you going to indent them five spaces? One-half inch? No way. I know that’s what your typing teacher taught you, and if you ever type across a page on a typewriter (if you can even find one) you usually need a five-space indent in proportion to the line length. But you are rarely setting lines that long on your computer, and besides, the standard typographic indent is one em space. An em space is a blank space as wide as the point size of the type; in 12-point type, an em space is 12 points; in 36-point type, it is 36 points. If you can set an indent with a measurement, set one em space. Otherwise fake it—an em space is more like two spaces than five.

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