The WCAG contrast ratios define the minimum colour contrast between text and background for accessibility. Level AA is the common legal standard; AAA is stricter.
| Content | Level | Minimum ratio |
|---|---|---|
| Normal text | AA | 4.5 : 1 |
| Normal text | AAA | 7 : 1 |
| Large text (≥18pt / 14pt bold) | AA | 3 : 1 |
| Large text | AAA | 4.5 : 1 |
| UI components & graphics | AA | 3 : 1 |