Color Contrast Checker — WCAG Accessibility

About Color Contrast Checker

The Web Content Accessibility Guidelines (WCAG) 2.1 define minimum contrast ratios to ensure text is readable for people with visual impairments. Level AA requires 4.5:1 for normal text and 3:1 for large text. Level AAA requires 7:1 and 4.5:1 respectively.

This tool calculates the contrast ratio between any two colors using the WCAG relative luminance formula and shows pass/fail results for both AA and AAA standards.

The WCAG contrast ratio is calculated from the relative luminance of two colors. Relative luminance accounts for how the human eye perceives brightness differently across the color spectrum — green appears brighter than blue at the same hex value. The formula applies gamma correction to sRGB values before computing the ratio, which ranges from 1:1 (no contrast) to 21:1 (black on white).

Approximately 300 million people worldwide have color vision deficiency. The most common form, deuteranomaly (red-green), affects 6% of males. Relying solely on color to convey information (like red for errors, green for success) fails for these users. Sufficient contrast ratio is the first step toward accessible design, but also consider using icons, patterns, or text labels alongside color.

Use this checker alongside the Color Converter to find accessible alternatives when a brand color fails contrast requirements. Small adjustments to lightness or saturation can often achieve the required 4.5:1 ratio while staying visually close to the original brand color. Test your final colors on both light and dark backgrounds.