WCAG Contrast Checker
Test any two colors against WCAG 2.2 accessibility standards. Get exact contrast ratios and immediate Pass/Fail results for AA and AAA, for both normal and large text.
What Is WCAG Contrast?
WCAG (Web Content Accessibility Guidelines) defines minimum contrast ratios between text and background so that content is readable for users with low vision, color blindness or anyone using a screen in poor lighting. It is published by the W3C and version 2.2 is the current standard for web accessibility.
The contrast ratio compares the relative luminance of two colors and produces a number from 1:1 (identical) to 21:1 (black on white). Higher is better. Text must meet a minimum ratio to pass each WCAG level.
WCAG 2.2 Requirements
| Level | Normal Text | Large Text |
|---|---|---|
| AA | 4.5:1 | 3:1 |
| AAA | 7:1 | 4.5:1 |
Large text is defined as 18pt (24px) or larger, or 14pt (18.66px) or larger when bold.
How the Checker Works
OmniColor computes the exact relative luminance for each color using the WCAG formula, then calculates the contrast ratio as (L1 + 0.05) / (L2 + 0.05) where L1 is the lighter color's luminance. The result is compared against the four thresholds and reported as Pass/Fail.