Contrast Checker
Check a foreground and background pair against WCAG 2.x AA and AAA contrast thresholds.
Enter values
The background cannot be transparent. A translucent foreground is composited over the background before calculation.
Contrast result
Readability sample Aa
About this tool
The ratio uses the WCAG 2.x relative-luminance formula. Black on white produces the maximum 21:1 ratio, followed by AA and AAA text checks.
Pass results cover text contrast only. Font weight, actual text size, controls, and other accessibility requirements still need separate review.
Frequently asked questions
What is the difference between AA and AAA?
AAA requires a higher contrast ratio than AA.
What counts as large text?
WCAG defines it by font size and weight; this tool reports the threshold but cannot infer your final CSS.
Can I use a transparent foreground?
Yes. Foreground alpha is composited over the background before calculation.
Related tools
Share if this helped