Glossary · Accessibility and provenance
contrast ratio
The luminance ratio between text and its background, which WCAG requires to be at least 4.5 to 1 for normal text and 3 to 1 for large text.
What contrast ratio means
The luminance ratio between text and its background, which WCAG requires to be at least 4.5 to 1 for normal text and 3 to 1 for large text. It must hold in hover and focus states as well as at rest, which is where most passing pages fail; a check that reads only the resting colours misses it.
What contrast ratio can and cannot support
| It can support | It cannot support |
|---|---|
| The luminance ratio between text and its background, which WCAG requires to be at least 4.5 to 1 for normal text and 3 to 1 for large text. | It must hold in hover and focus states as well as at rest, which is where most passing pages fail; a check that reads only the resting colours misses it. |
Related terms in Accessibility and provenance
What a page owes a keyboard, a screen reader and a fact-checker: the accessibility basics and the C2PA vocabulary for proving where a file came from.
Keyboard accessibility · Focus order · Focus indicator · ARIA · Accessible description · Color contrast · Reduced motion · Captions · Audio description · Status message · Content Credential · C2PA assertion · C2PA claim · Claim signature · Manifest store · Content binding · Hard binding · Soft binding · Ingredient · Trust list · landmark
Questions about contrast ratio
What is contrast ratio?
The luminance ratio between text and its background, which WCAG requires to be at least 4.5 to 1 for normal text and 3 to 1 for large text.
What does contrast ratio not show or guarantee?
It must hold in hover and focus states as well as at rest, which is where most passing pages fail; a check that reads only the resting colours misses it.
Which area of the glossary does contrast ratio belong to?
Accessibility and provenance: What a page owes a keyboard, a screen reader and a fact-checker: the accessibility basics and the C2PA vocabulary for proving where a file came from.
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See it in the full glossary · 668 terms across 19 areas.