Color Contrast Checker

A color contrast ratio measures the difference in luminance between two colors, expressed as a number from 1:1 (no contrast) to 21:1 (maximum contrast, black on white). It matters because insufficient contrast makes text difficult or impossible to read for people with low vision, color blindness, or those using screens in bright environments. WCAG 2.1 sets minimum contrast ratios to ensure web content is readable by the widest possible audience.

WCAG 2.1 defines two conformance levels for contrast. Level AA (minimum) requires a 4.5:1 ratio for normal text and 3:1 for large text (18px bold or 24px regular). Level AAA (enhanced) requires 7:1 for normal text and 4.5:1 for large text. Most accessibility laws and guidelines reference AA as the baseline requirement. Meeting AAA provides the best readability for all users.

Under WCAG 2.1, large text is defined as text that is at least 18 point (24 CSS pixels) at regular weight or 14 point (approximately 18.66 CSS pixels) at bold weight. Large text has a lower contrast requirement (3:1 for AA, 4.5:1 for AAA) because larger characters are inherently easier to read. Headings often qualify as large text, while body copy typically falls under the normal text thresholds.

To fix a failing contrast ratio, you can darken the text color, lighten the background (or vice versa), or adjust both. Our tool suggests the nearest accessible alternatives automatically. A common approach is to keep the hue and saturation similar while adjusting the lightness. You can also try increasing font weight or size to qualify for the less strict "large text" thresholds.

In many jurisdictions, yes. In the United States, the ADA (Americans with Disabilities Act) has been interpreted to apply to websites, and courts have referenced WCAG 2.1 AA as the standard. The EU Web Accessibility Directive requires WCAG 2.1 AA for public sector websites. Canada, Australia, and the UK have similar regulations. Beyond legal requirements, meeting WCAG standards improves usability for everyone and can boost SEO rankings.