WCAG Contrast Checker

Why Color Contrast Matters

Low-contrast text is one of the most common accessibility failures on the web. When foreground and background colors are too similar, people with low vision, color blindness, or situational impairments (like reading in bright sunlight) simply cannot read the content. An estimated 300 million people worldwide have some form of color vision deficiency — designing with contrast in mind means designing for everyone.

WCAG 2.2 defines specific contrast ratios that interfaces must meet to be considered accessible. The AA level (4.5:1 for normal text, 3:1 for large text) is the legal minimum in most countries, including the EU under EN 301 549 and the US under Section 508. The stricter AAA level (7:1 for normal text) is recommended for body copy and critical interfaces like healthcare and government portals.

Beyond legal compliance, high contrast improves readability for all users — not just those with disabilities. Studies consistently show that adequate contrast reduces eye strain, speeds up reading comprehension, and increases trust in a product. It is one of the cheapest accessibility wins available to any design team.

How the Calculation Works

The contrast ratio is calculated using the WCAG relative luminance formula: each color is converted from sRGB to linear light values, then combined as (L1 + 0.05) / (L2 + 0.05), where L1 is the lighter color. The result ranges from 1:1 (identical colors) to 21:1 (black on white).