Contrast Checker
Check WCAG AA and AAA contrast ratios instantly.
What is Contrast Checker?
A free WCAG contrast checker for developers and designers. Test any foreground/background color pair and see pass/fail results for AA and AAA compliance across normal and large text sizes. Built to match the WCAG 2.1 relative luminance specification exactly.
Frequently asked questions
+What is a WCAG contrast ratio?
The contrast ratio is a number from 1:1 (no contrast) to 21:1 (black on white) that describes the perceptual difference between two colors. WCAG 2.1 uses relative luminance to calculate it and sets thresholds for accessibility.
+What contrast ratio is required for accessibility?
WCAG AA requires 4.5:1 for normal text and 3:1 for large text (18pt+ or 14pt+ bold). WCAG AAA is stricter: 7:1 normal, 4.5:1 large.
+Does this tool work for UI components?
Yes — for non-text UI components (buttons, icons, borders) WCAG 2.1 SC 1.4.11 requires 3:1 against adjacent colors, matching AA Large.
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