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Color Contrast Checker Online Free — WCAG AA & AAA
Pick any foreground and background color pair and get the exact WCAG contrast ratio with AA/AAA pass-fail for normal and large text.
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Contrast Checker
WCAG 2.1 — 100% local
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The quick brown fox jumps over the lazy dog — sample text for your color pair.
| Requirement | Ratio | Result |
|---|---|---|
| AA — normal text | ≥ 4.5:1 | — |
| AAA — normal text | ≥ 7:1 | — |
| AA — large text | ≥ 3:1 | — |
| AAA — large text | ≥ 4.5:1 | — |
How to check color contrast (3 steps)
- Pick your two colors. Set the text (foreground) and the background — the preview updates live so you see the exact pairing.
- Read the ratio. The number (e.g. 12.3:1) is computed with the official WCAG relative-luminance formula, the same math audit tools use.
- Check the pass/fail table. AA (4.5:1 normal, 3:1 large) is the legal baseline in many places; AAA (7:1) is the gold standard for long-form reading. Large text = 18pt+ or 14pt+ bold.
Why contrast is an SEO and revenue issue
Low-contrast text does not just hurt readers with low vision — it kills readability on bright phone screens, which pushes up bounce rates, and Google's accessibility signals feed Core Web Vitals-adjacent rankings. Running every color pair through this checker takes seconds, and it is the single fastest accessibility win a site can make: no reflow, no script, no plugin — just two hex values.
FAQ
- What is "large text" exactly? 18pt (24px) regular, or 14pt (≈18.7px) bold and up — that is the WCAG definition used in the table.
- Does this match Lighthouse / axe results? Yes — it implements the identical WCAG 2.1 relative-luminance formula, so results match professional audit tools.
- Is my data sent anywhere? No — the calculation is two color values and some arithmetic, all local.
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