WCAG AA Contrast Checker
Verify minimum accessibility compliance
Okay,
We are what we repeatedly do; excellence, then, is not an act but a habit.
Aristotle
What is WCAG 2.1 AA?
WCAG AA is the minimum accessibility standard most organizations must meet. It requires a contrast ratio of at least 4.5:1 for normal text and 3:1 for large text (18pt+ or 14pt+ bold). These thresholds ensure text remains readable for most users with visual impairments.
AA compliance is often legally required. The ADA, Section 508, and many international laws reference WCAG AA as the baseline for web accessibility. Failing to meet these standards exposes organizations to legal risk.
Why WCAG 2.1 AA Matters
AA compliance balances accessibility with design flexibility. The 4.5:1 ratio allows many color combinations that both look good and remain accessible. It's achievable without sacrificing brand identity or visual appeal.
Most users with low vision can read text meeting AA standards. While not perfect for everyone, it significantly improves legibility for the approximately 8% of men and 0.5% of women with color vision deficiency.
WCAG 2.1 AA Requirements
**Normal text (under 18pt):** 4.5:1 minimum ratio
**Large text (18pt+ regular or 14pt+ bold):** 3:1 minimum ratio
**UI components and graphics:** 3:1 minimum ratio
The ratio compares luminance values of foreground and background colors. Pure white on black achieves 21:1—the maximum possible ratio.
How to Pass WCAG 2.1 AA
- Use our checker before finalizing color choices
- Test both light and dark mode combinations
- Check hover and focus states too
- Verify against actual background images
Pro Tip
When a combination barely fails AA (like 4.2:1), slightly darkening the darker color or lightening the lighter one often crosses the threshold.
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