What contrast ratio should I aim for?

For body text, aim for WCAG AA (4.5:1) at minimum — this is the legal accessibility standard in the EU (EAA) and matches Lighthouse's minimum score. AAA (7:1) is stricter and recommended for text-heavy sites and accessibility-first products. Large text (18pt+ or 14pt+ bold) has a lower bar: 3:1 for AA, 4.5:1 for AAA.

Does this match WebAIM and Lighthouse?

Yes. The ratio is computed using the official W3C WCAG 2.1 relative-luminance formula (sRGB, gamma-corrected). Results will match WebAIM Contrast Checker, Google Lighthouse, and axe-core exactly.

What is "large text" in WCAG?

Large text is 18pt (24px) or larger, OR 14pt (18.66px) or larger if bold. Everything else is "normal text." Large text has a lower contrast bar because bigger characters remain legible at lower ratios.

What about non-text UI (buttons, icons, borders)?

WCAG 2.1 SC 1.4.11 (Non-text Contrast) requires 3:1 for essential graphical elements — button borders, focus rings, icons that convey meaning, form field borders. This tool's "AA Large 3:1" badge is the right target for those elements.

Does the ratio account for opacity or backdrops?

No — the tool uses opaque HEX values. If your text has opacity or sits over an image/gradient, compute the "effective" background color first (blend RGBs at the alpha value) and paste that into the background field.

Is my data sent to a server?

No. Contrast math happens in your browser — brand palette HEX values are never sent anywhere.

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Bug reports, feature ideas, anything at all.

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WCAG Color Contrast Checker Online

Check WCAG 2.1 color contrast ratio for AA and AAA compliance. WebAIM-compatible results in real time — free, no signup.

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WCAG Color Contrast Checker Online

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