WCAG Font Size Checker
Text style
Checks
1.4.12 text-spacing minimums
| Property | Requirement | At 16px |
|---|---|---|
| Line height | ≥ 1.5 × font size | 24px |
| Paragraph spacing | ≥ 2 × font size | 32px |
| Letter spacing | ≥ 0.12em | 1.92px |
| Word spacing | ≥ 0.16em | 2.56px |
Readers must be able to apply these without any loss of content or functionality — never lock line-height with fixed pixel heights.
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The WCAG font size checker takes one text style and reports it against the success criteria that actually govern size and spacing, not only the contrast rule. Enter size, weight, measured contrast ratio and required zoom, and it classifies the text and scores each criterion.
What is WCAG Font Size Checker?
The WCAG font size checker evaluates a single text style against four numbered success criteria and returns a pass or fail for each, with the thresholds that applied written next to the result.
- Contrast (Minimum), 1.4.3, requires 4.5 to 1 for normal text and 3 to 1 once the text is classified as large.
- Contrast (Enhanced), 1.4.6, raises those to 7 to 1 and 4.5 to 1 for the same two classes.
- Large-text classification follows WCAG: 24px or more at any weight, or 18.66px or more at weight 700, with the point equivalent reported as the pixel size multiplied by 0.75.
- Resize text, 1.4.4, is scored against the zoom level you enter: support up to 200 percent passes outright, and beyond 200 percent the check only passes when the base size is at least 16px.
- Text spacing minimums from 1.4.12 are reported as four values converted to pixels at the current size: line height at 1.5 times the size, paragraph spacing at twice the size, letter spacing at 0.12em and word spacing at 0.16em.
The check list deliberately mixes hard criteria with best practice. AA contrast, AAA contrast, the body-text norm and the resize condition are scored and counted, while the large-text classification is printed as information rather than a verdict, which keeps the failure count in the results panel honest. Everything recomputes from the four inputs, so the spacing table moves the moment the size changes: at 16px it asks for 24px of leading, 32px between paragraphs, 1.92px of tracking and 2.56px of word spacing, and a reader has to be able to apply all four without losing content or functionality. The note under the table warns against locking line height with fixed pixel heights, which is the usual way a compliant-looking style fails the criterion in practice.
- The contrast ratio is typed in rather than measured from two colours, so this tool answers which thresholds apply rather than whether a specific pair meets them.
- The spacing minimums are targets. Nothing inspects a stylesheet or verifies that a declaration survives a user stylesheet being applied over it.
- Reflow at 320 CSS pixels, focus appearance and target size sit outside the four criteria evaluated here.
- The 16px body-text figure is a widely used norm rather than a WCAG minimum, and the panel labels it as best practice for that reason.
- A fixed pixel height on a text container is not detected, even though it is the commonest reason the spacing overrides fail.
Use it as the checklist for a type style before a design review: quote the classification, both contrast thresholds and the four spacing minimums for the size in question, and the conversation stops being about taste. When a style fails, fix the ratio first, since contrast is measurable and unambiguous, then move to spacing. To measure a candidate pair rather than a claimed ratio, the contrast text checker returns the real figure, the CSS line height tool covers the leading end of the spacing criterion, and the mobile font size checker handles the case where the base size passes on a desktop and fails on a phone.
How to use WCAG Font Size Checker
- Enter the font size in pixels and select the weight, so the tool can decide whether the style is treated as large text.
- Type the contrast ratio you measured for the pair, and set the zoom level the design has to survive.
- Work through the check list, reading the detail line under each criterion — it states the threshold that applied and the value you supplied.
- Copy the four text-spacing minimums from the table at your chosen size and verify them against the stylesheet, remembering that a fixed pixel height will defeat them.
When to use WCAG Font Size Checker vs related tools
Reach for it when a type style has to be defended against a checklist, when a designer wants to know whether 18px counts as large text, or when the spacing minimums for a given size need to be written down before a build. It is particularly useful in review, because each row states the requirement next to the measured value, which turns a vague objection into a specific number. For a full specification rather than one style, the font accessibility evaluator scores contrast, resize, spacing and reflow together, and the body text legibility grader judges how the result actually reads.
Privacy & Security
This tool runs entirely in your browser — no data ever leaves your device. There is no server round-trip, no upload, no logging, and no account required. Your input is processed locally using client-side JavaScript and is never stored, transmitted, or accessible to anyone else. When you close the tab, everything disappears.