WCAG contrast checker

Check opaque sRGB text and background against WCAG AA and AAA using the unrounded ratio.

Your input

Outputs are cleared when the input changes.

Result

Enter your data or use the example, then run the tool.

Worked example

Black/white is 21:1; #777777/white is about 4.478:1 and fails normal-text AA despite rounding close to 4.5.

Method

Linearize sRGB channels, compute relative luminance and compare (lighter + 0.05) / (darker + 0.05) at full precision.

Limits

Opaque hex colors only. Large-text and non-text applicability requires separate checks; this is not a complete accessibility audit.

Sources

W3C minimum contrast

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