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Glossary Design & Media

Colour contrast

Colour contrast is the difference in luminance between text and its background; WCAG expresses it as a ratio from 1:1 to 21:1.

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In more detail

Level AA needs at least 4.5:1 for normal text and 3:1 for large text; AAA needs 7:1 and 4.5:1. Black on white is 21:1, and #767676 on white is 4.54:1, the lightest neutral grey that passes AA for body text.

Try these tools

Color Contrast Checker

Check the contrast ratio between two colors against WCAG AA and AAA accessibility standards, computed instantly in your browser.

See also

  • Glossary Colour blindness
    Colour blindness, or colour vision deficiency, is a reduced ability to tell certain colours apart, most often red from green.
  • Guide How Color and Contrast Work
    Hex, RGB and HSL are one colour, how the WCAG contrast ratio is computed with real pass and fail examples.
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