Check whether a text column holds 45 to 75 characters per line and get a line-height to match
Measure and leadingFreeFor designers and developers
25/day
free runs a day, no sign-in.
Before: what you give it
The example input, as typed in. You type in numbers or values.
fontSizePx: 18 containerPx: 720 language: en
After: what comes back
The first lines of a real run on that input. Nothing here is edited by hand.
Measure: 80 characters per line (estimated at 0.5em average character width, en) Target range 45–75, ideal near 65: LONG Measure is long (over 75). The eye loses its place on the return sweep. Narrow the column or increase the type size. Recommended line-height: 1.63 (29.34px at 18px) Paragraph spacing: margin-block-end of 1.63em (one blank line), or no gap and a first-line indent of 1em. Use one, not both. Container for 45–75 characters at this size: 405–675px; for 65: about 585px (CSS: max-width: 65ch). The 45 to 75 range is Bringhurst's measure guidance as reported by Smashing's Typography Best Practices. The leading curve and the 1em indent are conventions.
What you get
Characters per line, in-range verdict, recommended line-height, paragraph spacing and a target width
What it cannot do
Width is estimated from an average character width, so it is a guide; the leading curve is a convention.
Who it is for
- Designers
- Developers
Free and Pro
| Free | 25 runs a day per IP address. |
|---|---|
| Pro | No daily limit, 300 requests a minute. |
Use it from your assistant
The tool is called measure_leading. Connect the server once, then ask for it by name or just describe the job. Install steps for each app.
claude mcp add --transport http designers https://designers.allthepossibles.com/mcpcurl -X POST https://designers.allthepossibles.com/api/measure-leading -H 'content-type: application/json' -d '{"fontSizePx":18,"containerPx":720,"language":"en"}'Try it here
The form starts with the same example input, so you can run it first and then swap in your own.
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