// Accessibility
The luminance difference between text and its background, expressed as a ratio (e.g. 4.5:1). WCAG AA requires 4.5:1 for normal text and 3:1 for large text. Low contrast makes text unreadable for users with low vision and fails WCAG compliance checks.
Why it matters: Color Contrast Ratio is one of the accessibility signals that shapes how search engines, AI tools, and real visitors experience your website. Getting it right removes friction, protects your rankings, and makes every other optimization work harder. Auditing it regularly is the fastest way to catch regressions before they cost you traffic or conversions.
See how your own site handles color contrast ratio — no signup required.
Check your site's Color Contrast Ratio — run the free Accessibility Agent