Color Blindness Simulator

The most common are red-green deficiencies: protanopia (reduced red sensitivity) and deuteranopia (reduced green). Tritanopia is a rarer blue-yellow deficiency, and achromatopsia is total color blindness where only brightness is perceived. This tool simulates all four.

Simulators apply well-established transform matrices that approximate how dichromats perceive color. They are a strong first-pass check for design decisions, but individual experiences of CVD vary, so they estimate rather than reproduce exact perception.

Never rely on color alone to convey meaning. Add labels, icons, patterns or text, ensure sufficient lightness contrast between important elements, and avoid red/green as the only distinction between states like success and error. Test key screens with a simulator.

For the common red-green types, red versus green and combinations like green/brown or blue/purple can be difficult. Pairs that differ mainly in hue but not in brightness are the most problematic; differences in lightness survive most types of color blindness.

It affects roughly 8% of men and 0.5% of women of Northern European descent — about 1 in 12 and 1 in 200 respectively. Red-green deficiency is by far the most common form, which is why it dominates accessibility guidance.