Contrast Checker
Check the contrast ratio between two colors against WCAG. Accessible by default.
WCAG AA WCAG AAA Ratio
21.0:1
WCAG AA
WCAG AAA
How it works
1
Pick colors
Choose foreground and background colors.
2
Check ratio
The contrast ratio is computed instantly.
3
See rating
WCAG AA and AAA levels are shown.
Why use Ercc Contrast Checker?
Accurate
Uses the official WCAG relative luminance formula.
Clear
Shows AA/AAA pass-fail for text and UI.
Local
Everything runs in your browser.
FAQ
Frequently Asked Questions
A ratio from 1:1 (same color) to 21:1 (black on white), computed from relative luminance.
Normal text needs 4.5:1, large text 3:1, and UI components 3:1.
Normal text needs 7:1 and large text 4.5:1.
Yes, 100% free.
Yes, it follows the official WCAG 2.x formula used in design tools.