Contrast checker — WCAG AA and AAA
Enter a text colour and a background and see the exact WCAG contrast ratio, with pass/fail for AA and AAA. It checks in your browser (0 uploads, works offline).
How to use it
- Enter your input above.
- The result appears live on your device.
- Copy or Download it.
FAQ
How do I check colour contrast for accessibility for free?
Enter the text and background colours and the WCAG contrast ratio appears instantly in your browser with no upload, along with whether it passes AA (4.5:1) and AAA (7:1) for normal and large text — with a live preview of the two colours together.
What contrast ratio do I need?
WCAG AA requires 4.5:1 for normal text and 3:1 for large text (18pt or 14pt bold); AAA requires 7:1 and 4.5:1. The tool computes the exact ratio using the official luminance formula, not an approximation.
Is anything uploaded?
No. The calculation is local and nothing is stored; it works offline.
Why does contrast matter?
Low contrast makes text hard or impossible to read for people with low vision — it is one of the most common accessibility failures, and one of the easiest to fix.
Limits
Uses the WCAG 2.1 luminance formula. APCA (the WCAG 3 draft method) is not yet included.
Related
The colour converter changes formats; the palette generator builds accessible colour sets.
Bookmark this page (Ctrl+D, or ⌘D on Mac) or install the app — it works offline the next time you need it.