Color Contrast Checker Documentation

Check the contrast ratio between two colors against WCAG AA and AAA accessibility thresholds.

SiteIndex computes the relative luminance of your foreground and background colors and derives the WCAG contrast ratio, then flags whether it passes AA and AAA thresholds for normal and large text.

• Confirm body text meets WCAG AA contrast before shipping a design.
• Check large heading text against the more lenient AAA large-text threshold.
• Compare a few color pairs to find an accessible combination.

Input

Text, files, or values entered in the browser, depending on the tool.

Output

A result shown in the browser that can be reviewed or copied where supported.

• Results depend on the input, browser, network, and external service involved.
• This tool is informational and does not replace specialist diagnostics.

Inputs for this browser-side tool are processed locally and are not sent to SiteIndex. Normal page analytics may still be collected as described in the Privacy Policy. Read the Privacy Policy.