Color Blindness Simulator
Preview how a color appears to people with protanopia, deuteranopia, tritanopia or achromatopsia.
Quick answer: Color Blindness Simulator: preview how a color appears to people with protanopia, deuteranopia, tritanopia or achromatopsia. Runs entirely in your browser, free, no signup.
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Roughly one in twelve men and one in two hundred women have some form of color vision deficiency, so a color scheme that reads clearly to you may collapse into indistinguishable grays for a meaningful slice of your audience. This simulator applies the transformation matrices used in accessibility research to preview four types: protanopia (missing red cones), deuteranopia (missing green cones), tritanopia (missing blue cones) and achromatopsia (no color perception at all).
Red–green confusion is by far the most common, which is exactly why the traditional red-for-error, green-for-success convention is risky on its own. If red and green are your only signal, protanopes and deuteranopes may see the two states as the same muddy tone. The fix is not to avoid color but to add a second, redundant cue — an icon, a label, a shape or a pattern — so meaning survives even when the hue does not.
Use this alongside contrast testing rather than instead of it: a palette can be color-blind-safe yet still fail luminance contrast, or vice versa. After confirming your pairs stay distinguishable here, run the actual text and background through the WCAG contrast checker, and sample or adjust individual values with the color picker.
Frequently asked questions
- Is it free?
- Yes — free with no signup.
- Which types are simulated?
- Protanopia (red-blind), deuteranopia (green-blind), tritanopia (blue-blind) and achromatopsia (full color-blindness).
- Are the matrices accurate?
- Yes — they're the Brettel/Viénot/Mollon matrices used in academic research and accessibility tooling.
- Should I rely on color alone in my UI?
- No — always pair color with another cue like text, icon or shape so color-blind users aren't excluded.
- Is anything uploaded?
- No — every simulation runs in your browser.