Color Blindness Simulator
Free tool that simulates how a color appears to people with protanopia, deuteranopia, or tritanopia (color vision deficiency).
The three types of color vision deficiency
| Type | Name | Characteristics |
|---|---|---|
| Protanopia | Red-blind (L-cone deficiency) | The red-sensing cones function differently, making red and green harder to distinguish. |
| Deuteranopia | Green-blind (M-cone deficiency) | The green-sensing cones function differently, making red and green harder to distinguish. The most common type of color vision deficiency. |
| Tritanopia | Blue-blind (S-cone deficiency) | The blue-sensing cones function differently, making blue and yellow harder to distinguish. Very rare. |
Tips
- Pick a color with the color picker or type a hex code to instantly see how it looks under protanopia, deuteranopia, and tritanopia.
- Use this tool before publishing a design to check whether your color palette remains distinguishable for people with color vision deficiency.
- Red and green combinations are especially hard to tell apart, so it's worth checking charts and maps that rely on this pairing.
- The simulation is a simplified approximation, so for critical accessibility decisions you should also use dedicated tools and real user testing.
Frequently Asked Questions
Side Note — The history of color vision testing and the Ishihara test
Color vision deficiency affects an estimated 1 in 20 men and 1 in 500 women of Japanese descent, and reports suggest roughly 8% of men worldwide are affected. It is far from rare — statistically, there is likely at least one person with this trait in any given classroom or workplace.
The best-known color vision test, the Ishihara Color Test, was devised in 1917 by Japanese ophthalmologist Shinobu Ishihara. Its distinctive plates, which hide numbers or shapes among clusters of colored dots, were originally developed for color vision screening during military conscription exams, and the same design is still used in eye clinics around the world more than a century later.
In web and app design, relying too heavily on color — such as a chart that shows pass or fail only in red and green, or a map that distinguishes routes by color alone — can leave out information for a meaningful share of users. Checking color combinations with a simulation beforehand and pairing them with icons, patterns, or text labels is a basic practice of inclusive design that benefits everyone.