Line Length Calculator

This calculator estimates how many characters fit on a line of text by dividing your usable column width (container width minus side padding, doubled) by the average character width in pixels — which it derives by multiplying font size by an em-based width fraction you supply (0.45 for a typical serif, 0.50 for sans-serif, 0.38 for condensed faces, up to 0.60 for monospace, where a character is exactly one "ch" unit wide). It then scores the result against the range of 45 to 75 characters per line that Robert Bringhurst's "The Elements of Typographic Style" identifies as the sweet spot for sustained reading -- in the book's own words, "anything from 45 to 75 characters is widely regarded as a satisfactory length of line," with 66 characters as the textbook ideal -- the readability rating peaks there and falls off faster below the minimum than above the maximum, since lines that are too short force the eye to jump back constantly while lines that are merely long are easier to tolerate. It also works backward, telling you the container width that would produce exactly 45, 66, or 75 characters at your chosen font size, which is the more actionable number when you're setting up a CSS column or print layout.

The words-per-line figure is a rough guide only, using a flat six-character average (five letters plus a space) that doesn't account for your actual copy's word length or language. The biggest source of error is the average character width input itself: it's a single approximation for an entire typeface at a given size, when real fonts have letters ranging from "i" to "m," so treat the character count as directional guidance rather than a precise typesetting measurement, and always sanity-check the recommended width by looking at real rendered text.