Check a color pair
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| Content | Required ratio | AA | AAA | |
|---|---|---|---|---|
| Normal text (< 18pt / < 14pt bold) | 4.5 : 1 | — | — | |
| Large text (≥ 18pt or ≥ 14pt bold) | 3 : 1 | — | — | |
| UI components & graphical objects | 3 : 1 | — | n/a | |
Large heading preview
This is how normal body text looks in your chosen combination. Readable at length? Your readers will decide in seconds.
Ratios follow WCAG 2.1 success criteria 1.4.3 (Contrast Minimum), 1.4.6 (Contrast Enhanced) and 1.4.11 (Non-text Contrast). Fixing failures site-wide? The free Accessibility Scanner finds low-contrast text on a whole page.
How the ratio is calculated
Each color is converted to sRGB relative luminance (L = 0.2126·R + 0.7152·G + 0.0722·B after gamma expansion). The contrast ratio is (L1 + 0.05) / (L2 + 0.05), where L1 is the lighter color. A ratio of 1:1 means identical colors; 21:1 is the maximum (black on white). This matches the formula in the WCAG specification exactly.
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