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ToolWrenSee how any color appears to people with the main types of color vision deficiency — essential for accessible design.
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Color Blindness is a free, private online tool that lets you preview how a color looks to people with the common types of color vision deficiency. It runs entirely in your browser, so nothing you enter is uploaded to a server.
Privacy: this tool runs entirely in your browser. Your input is never sent to, received by, or stored on any server — there are no uploads and no tracking of what you enter.
About 1 in 12 men and 1 in 200 women have some form of color blindness. The most common types affect red-green perception (protanopia, deuteranopia); tritanopia affects blue-yellow, and achromatopsia is total color blindness.
Pick a color and the tool shows it as seen with normal vision alongside each simulated deficiency, so you can spot colors that become indistinguishable.
Avoid relying on color alone to convey meaning, and test key UI colors here to ensure they remain distinguishable for everyone.
A color blindness simulator shows how a given color appears to people with the common types of color vision deficiency (CVD). You pick a color and see it rendered as someone with each condition would perceive it, side by side with normal vision - a fast way to spot colors that become hard to tell apart.
Color vision deficiency is far more widespread than many designers realise: it affects roughly 1 in 12 men and 1 in 200 women. That means in any sizeable audience a meaningful fraction cannot distinguish certain color pairs, so designs that rely on color alone can fail a large group of users.
The tool covers the main forms. Protanopia and deuteranopia are red-green deficiencies (by far the most common), making reds, greens and browns easy to confuse. Tritanopia is a rarer blue-yellow deficiency. Achromatopsia is total color blindness, where everything appears in shades of grey. Seeing all of these reveals which colors collapse together.
Each deficiency is approximated with a standard color-transformation matrix applied to the color's red, green and blue values. These matrices model how the missing or altered cone cells change perception. The result is a close approximation - real perception varies between individuals - but it is more than accurate enough to catch problem combinations.
The practical lesson is to never rely on color alone to convey meaning. Pair color with text labels, icons, patterns or shapes; ensure status indicators (red/green) are also distinguishable by shape or wording; and check charts and maps. Use this simulator on your key UI colors, and the Contrast Checker for readability, to make designs work for everyone.