Choose text and background colors. See the contrast ratio, AA and AAA results, live previews, and same-hue adjustments for the selected threshold.
Runs entirely in your browser. Nothing you enter leaves this page.
Enter hex values or use the color pickers. Every readout updates locally.
Swap flips text and background - a pair can pass one way and feel different the other.
Passes AA for all text; AAA for large text.
Large text = at least 24px regular or 18.66px bold. UI components covers borders, icons, and focus indicators (WCAG 1.4.11).
Every number this tool shows, and where it comes from.
The formula. Each color’s relative luminance is computed per the WCAG definition (sRGB channels linearized, then weighted 0.2126 R + 0.7152 G + 0.0722 B), and the ratio is (L1 + 0.05) / (L2 + 0.05). This is the exact math auditors and browsers’ dev tools use. Reference: Understanding SC 1.4.3.
The thresholds. AA requires 4.5:1 for normal text and 3:1 for large text (SC 1.4.3); AAA raises those to 7:1 and 4.5:1 (SC 1.4.6); non-text UI components - input borders, icons, focus rings - need 3:1 (SC 1.4.11). Large means at least 18pt (24px), or 14pt (about 18.66px) bold.
How the suggestions work. The tool holds your color’s hue and saturation and walks its lightness until the pair clears the target ratio, so the fix still looks like your brand. When no same-hue shade can pass - two mid-tones, for instance - it says so instead of inventing a different color.
One ratio is not an audit. Contrast is a single criterion among dozens: color-only meaning, focus visibility, zoom behavior, and semantics are separate checks. For a second opinion on the math itself, WebAIM’s checker runs the same formula.
Why not APCA? The newer perceptual-contrast algorithm is a WCAG 3 draft, not a conformance standard. Legal and procurement requirements today cite WCAG 2.x, so this tool sticks to the math you can be held to.
Thresholds verified against WCAG 2.2 (W3C Recommendation) 2026-07-03.
The rest of the toolkit runs in your browser too.
Use Orbit’s Compliance system to organize broader accessibility checks and readiness work. Its outputs are indicators, not certifications.
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