Color Accessibility Checker
Check color contrast ratios against WCAG 2.1 guidelines. Test AA and AAA compliance for normal and large text. Free, 100% in your browser.
Large text preview (18pt+)
Normal body text preview — check readability against the background color.
Reference
What is WCAG color contrast?
The Web Content Accessibility Guidelines (WCAG) 2.1 define minimum contrast ratios to ensure text is readable by people with visual impairments. Contrast ratio ranges from 1:1 (no contrast) to 21:1 (maximum, black on white). About 8% of men and 0.5% of women have some form of color vision deficiency, making sufficient contrast essential for inclusive design.
WCAG conformance levels
AA — Normal text: minimum 4.5:1 contrast ratio (most common requirement). AA — Large text: minimum 3:1 (large = 18pt/24px regular or 14pt/18.5px bold). AAA — Normal text: minimum 7:1 (enhanced, recommended for body text). AAA — Large text: minimum 4.5:1. Most accessibility laws and standards (ADA, Section 508, EN 301 549) reference WCAG AA as the minimum requirement.
How contrast ratio is calculated
The contrast ratio uses relative luminance values derived from sRGB colors. Each color channel (R, G, B) is linearized: if the sRGB value ≤ 0.04045, divide by 12.92; otherwise compute ((value + 0.055) / 1.055)^2.4. Luminance = 0.2126·R + 0.7152·G + 0.0722·B. The contrast ratio = (L1 + 0.05) / (L2 + 0.05), where L1 is the lighter color's luminance and L2 is the darker.
Privacy
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