Test color combinations for WCAG accessibility compliance. Check contrast ratios for AA and AAA standards in real-time.
Instant contrast ratio calculation as you type or adjust colors
Check AA and AAA standards for normal and large text
Generate accessible color variations and harmonies
Export your accessible colors as CSS or SCSS variables
The Web Content Accessibility Guidelines (WCAG) define minimum contrast ratios to ensure text is readable for users with visual impairments:
4.5:1 for normal text, 3:1 for large text (18pt+ or 14pt+ bold)
7:1 for normal text, 4.5:1 for large text
3:1 minimum for graphical objects and user interface components
Contrast ratio measures the difference in brightness between two colors. A higher ratio means better readability. This is crucial for users with low vision, color blindness, or those viewing screens in bright environments. WCAG guidelines set minimum ratios to ensure content is accessible to everyone.
Level AA is the minimum recommended standard and is legally required in many jurisdictions. It requires 4.5:1 for normal text and 3:1 for large text. Level AAA is an enhanced standard (7:1 for normal text) that provides better accessibility but may not always be achievable for all design requirements.
Large text is defined as at least 18 point (24px) for regular weight, or 14 point (approximately 18.5px) for bold text. Large text has lower contrast requirements because its size makes it inherently easier to read.
Contrast ratio is calculated using the relative luminance of each color. The formula is (L1 + 0.05) / (L2 + 0.05), where L1 is the lighter color's luminance and L2 is the darker color's luminance. The result ranges from 1:1 (no contrast) to 21:1 (maximum contrast, black on white).
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