Color Contrast Checker (WCAG)

Color contrast is one of the most important factors in web accessibility. When text does not stand out enough from its background, users with low vision, color blindness, or screen glare struggle to read content. The Web Content Accessibility Guidelines (WCAG) define specific contrast ratios that help ensure text remains readable for the widest possible audience. This checker calculates those ratios instantly so designers and developers can verify color choices before shipping a design.

WCAG defines two conformance levels that matter for contrast. Level AA is the baseline that most websites and applications should meet. It requires a contrast ratio of at least 4.5:1 for normal-sized text and 3:1 for large text (18px bold or 24px regular). Level AAA is the enhanced standard, requiring 7:1 for normal text and 4.5:1 for large text. Meeting AAA is not always practical for every design, but it provides the best readability for people with moderate vision loss.

The tool uses the WCAG 2.1 algorithm, which converts sRGB color values to relative luminance and calculates the ratio between the lighter and darker color. This is the same formula used by professional accessibility auditing tools, so the results you see here match what an accessibility audit would report. Use it during design reviews, component development, or content updates to catch contrast issues early and avoid costly rework after launch.