What is the ideal line length for body text?

Aim for 45–75 characters per line, with 55–65 characters as a practical sweet spot for most body copy on the web.

Why use ch instead of px for max-width?

The ch unit approximates character width in the active font, so line length stays consistent when font size or family changes. Pixels do not track character count.

Does line length affect SEO?

Line length affects readability and engagement metrics like time on page and bounce rate. Readable text keeps users on content longer, which indirectly supports search performance.

Best Line Length for Reading — CSS Measure Guide

The best line length for reading on the web is roughly 45 to 75 characters per line. Research on reading comfort and eye movement consistently lands in this range. On most interfaces, 55 to 65 characters feels best.

Lines shorter than 45 characters force frequent eye jumps and break rhythm. Lines longer than 80 characters make the return saccade — the jump from the end of one line to the start of the next — unreliable, causing skipped lines and rereading.

Why developers get line length wrong

The common mistake is applying max-width to a page wrapper instead of the text container. Sidebars and heroes look bounded, but paragraphs inside still run the full column width on a 27-inch monitor.

Measure is a property of the text block, not the page layout. Every container holding reading text — paragraphs, list items, blockquotes — needs its own constraint.

CSS defaults that work

Use ch units so line length scales with the font. One ch equals the width of the zero character in the current font, which tracks character count better than pixels.

Set max-width: 65ch on p, li, blockquote, and .prose containers
Avoid applying max-width only to outer layout wrappers
Test on wide viewports — line length failures show up on large monitors

Interactive lessons

Related guides

Glossary

Frequently asked questions

What is the ideal line length for body text?: Aim for 45–75 characters per line, with 55–65 characters as a practical sweet spot for most body copy on the web.
Why use ch instead of px for max-width?: The ch unit approximates character width in the active font, so line length stays consistent when font size or family changes. Pixels do not track character count.
Does line length affect SEO?: Line length affects readability and engagement metrics like time on page and bounce rate. Readable text keeps users on content longer, which indirectly supports search performance.