Color Contrast Checker

WCAG (Web Content Accessibility Guidelines) defines minimum contrast ratios to ensure text is readable for people with visual impairments, including color blindness and low vision. Contrast ratio ranges from 1:1 (no contrast, same color) to 21:1 (maximum, black on white).

WCAG AA requires a minimum ratio of 4.5:1 for normal text and 3:1 for large text (18pt / 24px or 14pt bold). WCAG AAA is stricter: 7:1 for normal text and 4.5:1 for large text. UI components and graphical objects need at least 3:1 against adjacent colors.

The contrast ratio is calculated from the relative luminance of both colors using the formula defined in WCAG 2.1. Luminance accounts for how the human eye perceives different wavelengths — green appears brighter than blue at the same intensity. This tool calculates the exact ratio and checks against all WCAG levels so you can fix accessibility issues before shipping.