WCAG contrast checker
Check the contrast ratio between two colors and WCAG AA / AAA compliance.
🔒 100% client-side — no data sent
WCAG contrast checker to test the ratio between a text color and its background and validate AA and AAA accessibility. Perfect for making your interfaces readable by everyone and compliant with WCAG guidelines. The ratio is computed entirely in your browser; no color is ever transmitted.
FAQ
What contrast ratio is required to meet WCAG AA?
Level AA requires a ratio of at least 4.5:1 for normal text and 3:1 for large text. The tool instantly shows whether your colors pass.
What's the difference between AA and AAA levels?
AAA is stricter: it requires 7:1 for normal text and 4.5:1 for large text, versus 4.5:1 and 3:1 for AA. AAA targets maximum accessibility.
What counts as 'large text' under WCAG?
Text is considered large from 18 pt (24 px) regular, or 14 pt (18.66 px) bold. The contrast thresholds are more lenient in that case.
How is the contrast ratio calculated?
It compares the relative luminance of the two colors using (L1 + 0.05) / (L2 + 0.05), giving a value between 1:1 and 21:1. The tool applies this official W3C formula.