Enter two hex colors
Use three or six digits for one opaque foreground and background.
Normalize · calculate · review
One color pair. A ratio you can reproduce.
ContrastCheck turns two opaque hex colors into relative luminance, a raw WCAG 2.x ratio and five clearly named threshold references in your browser.
No account, upload, CSS crawler, saved palette, remote fetch or conformance claim.
Three explicit steps
Enter, calculate, verify in context
Read ratio and luminance
The current W3C sRGB transfer and luminance weights stay deterministic.
Match the real content context
Decide text category, states and adjacent colors outside the pair calculator.
Focused design arithmetic
Useful when a declared color pair needs a transparent check
- Compare a text token with a known solid surface.
- Verify a documented design-system pair at a named threshold.
- Reproduce a contrast result from normalized hex values.
- Explain why two nearby gray values straddle 4.5:1.
One opaque pair · local calculation
Check the same colors in ContrastCheck
Enter the foreground and background hex values to reproduce the raw WCAG 2.x ratio, five threshold references and a fixed preview without uploading either color.