WCAG Color Contrast Checker
Check WCAG color contrast ratios between two colors. Pass/fail for AA and AAA levels. Free accessibility tool.
Frequently asked questions
- What is a WCAG contrast ratio?
- It measures the brightness difference between text and background, from 1:1 (identical) to 21:1 (black on white).
- What are the pass thresholds?
- Level AA needs 4.5:1 for normal text and 3:1 for large text. Level AAA needs 7:1 and 4.5:1.
- How is the ratio calculated?
- Each color is converted to relative luminance using the sRGB formula, then compared as (lighter + 0.05) divided by (darker + 0.05).
- Are my colors uploaded?
- No. The calculation runs in your browser and nothing is transmitted.
This tool runs entirely in your browser. No data is uploaded anywhere.