Unkillable Access / WCAG colour contrast checker
WCAG colour contrast checker
Check every text element on a page against the WCAG 2.2 contrast ratios (4.5:1 normal, 3:1 large). Free, runs in your browser, cites the criterion.
WCAG 2.2 success criterion 1.4.3 requires a contrast ratio of at least 4.5:1 between text and its background, or 3:1 for large text — 24px and above, or 18.66px and above when bold.
This scanner computes the real ratio for every text element whose colours it can resolve from your HTML and CSS, and reports the exact figure alongside the threshold it needed to clear.
An important caveat about contrast tools
Where a background comes from an image, a gradient, or a colour set by JavaScript at runtime, the ratio is not statically determinable. We report those as undetermined and count them separately. We do not quietly treat them as passes, which would inflate the result and mislead you about your own site.
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