Paste real copy
Use actual paragraph text from your site so the measured line length reflects reality, not lorem ipsum.
Readable Line Length Tester
Paste your own body text, drag the max-width slider, and see how the resulting line length compares to the 45-75 character sweet spot.
How it works
Drag the width
The max-width is set in ch units — roughly the width of one character — the same unit typographers use to measure line length.
Read the badge
The badge below the preview tells you whether your average characters-per-line falls in the recommended 45-75 range.
FAQ
What is the ideal line length for reading?
Typography guidance generally recommends 45 to 75 characters per line for body text, with about 66 characters often cited as close to ideal. Lines much shorter or longer than this tend to slow reading down.
Why do long lines hurt readability?
On very long lines, readers' eyes have to travel further and are more likely to lose their place when jumping back to find the start of the next line, which increases reading fatigue.
Should mobile and desktop use the same line length?
Not necessarily in pixels, but the target character count stays similar. Because mobile screens are narrower, a max-width set in relative units like ch or em naturally keeps character counts consistent across screen sizes.