Free WCAG Color Contrast Checker
Pick a text color and a background color and instantly get the contrast ratio computed with the official WCAG 2.x formula. The tool shows whether the pair passes AA (4.5:1 normal text, 3:1 large text) and AAA (7:1 normal, 4.5:1 large) — the Web Content Accessibility Guidelines used in accessibility audits and by law in many regions.
What is a good contrast ratio?
Contrast ratio ranges from 1:1 (same color) to 21:1 (black on white). For body text, WCAG AA requires at least 4.5:1; large text (18px+ or 14px+ bold) needs 3:1. Aim for AA as a baseline — it covers roughly 1 in 8 color pairs on average, so low-contrast "design greys" fail quickly.
Contrast Checker FAQ
How is the ratio calculated? Using relative luminance per the WCAG formula, then (L1+0.05)/(L2+0.05). What's the difference between AA and AAA? AAA is stricter (7:1) and recommended for long reading text. Do I need to worry about large text? Large text gets a more lenient threshold because bigger glyphs are easier to read. Is my data sent anywhere? No — all calculations run in your browser.