👁️ Color Contrast Checker

Compute WCAG contrast ratio & pass/fail.

Check

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 How it works 
 
How it works
 
The WCAG 2.1 contrast ratio is computed from relative luminance in linear sRGB.
 
     
  • Gamma expand sRGB to linear: L = (c<=0.03928 ? c/12.92 : ((c+0.055)/1.055)^2.4).
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  • Relative luminance: 0.2126 R + 0.7152 G + 0.0722 B.
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  • Contrast ratio: (L1+0.05)/(L2+0.05) with L1 ≥ L2.
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Thresholds: AA 4.5 (normal text), 3.0 (large); AAA 7.0 (normal), 4.5 (large).
 
 
 
 Privacy & Security 
All calculations local.
 
  
 
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 Accuracy, Limits & Tips 
Only hex input; no alpha channel.
 
 
 Examples 
  • #000000 on #FFFFFF has 21:1 contrast.
 
 
 
 
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