Understanding WCAG Contrast Standards
The Web Content Accessibility Guidelines (WCAG) 2.1 define contrast ratios to ensure visual readability for users with low vision or color vision deficiencies.
WCAG 2.1 Requirements Overview
- WCAG AA (Minimum): Requires a contrast ratio of at least 4.5:1 for normal text (under 18pt/24px or 14pt/18.5px bold) and 3:1 for large text and essential UI components.
- WCAG AAA (Enhanced): Requires a contrast ratio of at least 7:1 for normal body text and 4.5:1 for large text.
- Relative Luminance: Calculated by converting sRGB values into linear color space according to standard CIE luminance metrics.