In typography, line length is the width of a block of typeset text, usually measured in units of length like inches or points or in characters per line. A block of text or paragraph has a maximum line length that fits a determined design.

The line or British line (abbreviated L or l) was a small English unit of length, variously reckoned as , , , or of an inch. It was not included among the units authorized as the British Imperial system in 1824.