Contrast Checker
Check whether your text and background colors meet WCAG accessibility contrast standards.
How it works
The Web Content Accessibility Guidelines (WCAG) measure readability with a contrast ratio from 1:1 (identical colors) to 21:1 (black on white). The ratio is computed from each color's relative luminance — roughly, how bright the color appears to the human eye, with green weighted far more heavily than blue because our eyes are most sensitive to it. To pass, normal-sized text needs a ratio of at least 4.5:1 for AA (the legal standard in most places) or 7:1 for AAA; large text (bold 14pt+ or 18pt+) gets a break at 3:1 and 4.5:1 because bigger glyphs are easier to read. Low contrast is one of the most common accessibility failures on the web, and it affects far more people than screen-reader users — anyone reading on a phone in sunlight benefits.