Understanding WCAG 2.1 Contrast Thresholds
Web Content Accessibility Guidelines (WCAG 2.1) require sufficient visual contrast between text and background colors to accommodate users with low vision or color vision deficiencies:
- Level AA (Normal Text): Requires a minimum contrast ratio of 4.5:1 for text under 18pt (or 14pt bold).
- Level AA (Large Text): Requires a minimum contrast ratio of 3.0:1 for text 18pt+ (or 14pt bold).
- Level AAA (Normal Text): Requires a contrast ratio of 7.0:1.
- Level AAA (Large Text): Requires a contrast ratio of 4.5:1.
Frequently Asked Questions
Why is web color contrast important?
Sufficient color contrast improves readability for visually impaired users and reduces eye strain for all website visitors under bright ambient light conditions.
Is color analysis executed locally?
Yes. Luminance and contrast ratios are computed 100% locally in your web browser using WCAG relative luminance algorithms.