Color Contrast

The difference in luminance between foreground text (or UI components) and their background, measured as a ratio. WCAG 2.1 requires a minimum contrast ratio of 4.5:1 for normal text and 3:1 for large text at Level AA, and 7:1 for normal text and 4.5:1 for large text at Level AAA. Insufficient color contrast is consistently the most common accessibility violation on the web, affecting over 79% of home pages according to the WebAIM Million 2025 study. Good contrast benefits all users, particularly those with low vision, color vision deficiencies, or those viewing screens in bright sunlight.