Line Length Calculator
Find the optimal line length for any font and container width. See your characters-per-line count in real time with a live preview and zone indicator.
Quick presets
Long-form reading optimized for comfort
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characters per line
← Optimal range: 45–75 CPL →
Live preview
Good typography is measured in the reading experience. Line length – the number of characters per line – directly affects reading speed, comprehension, and comfort. When lines are too short, the eye must jump to the next line too often, creating a choppy experience. When lines are too long, readers lose their place and struggle to find the beginning of the next line. The sweet spot for body text sits between 45 and 75 characters per line, with 65 being widely considered ideal for single-column layouts.
680px wide
Why Line Length Matters
Robert Bringhurst's The Elements of Typographic Style – the definitive reference for typography practitioners – recommends 45 to 75 characters per line as the comfortable range for body text, with 66 characters cited as the ideal. This isn't arbitrary: research on reading behavior shows that shorter lines force the eye to jump too frequently, interrupting reading flow, while longer lines make it difficult to track from the end of one line back to the beginning of the next. The saccadic eye movement that readers rely on becomes unreliable beyond ~80 characters.
The catch is that "characters per line" depends on both your container width and your font choice. A 680px container set in Georgia 18px yields roughly 65–70 CPL – well within the optimal zone. The same 680px container in Inter 14px would produce over 90 CPL – uncomfortably wide. This is why you can't specify a "correct" pixel width for readable content without knowing the font. Use this tool to tune both values together, preview the result on real text, and export exact CSS values ready for your codebase.