Color Blindness Simulator
See how any color looks through the eyes of someone with color vision deficiency. Test for protanopia, deuteranopia, tritanopia, and achromatopsia.
Quick Answer
About 8% of men and 0.5% of women have some form of color vision deficiency. The most common types confuse reds and greens. Enter a HEX color below to see how it appears under four types of color blindness, helping you design accessible interfaces.
Simulate Color Blindness
Enter a HEX color to see how it appears under different color vision deficiencies.
About This Tool
The Color Blindness Simulator helps designers, developers, and content creators understand how their color choices appear to people with color vision deficiency (CVD). Approximately 300 million people worldwide live with some form of color blindness, making this one of the most common visual impairments. By simulating four major types of CVD, this tool empowers you to build more accessible and inclusive designs.
Understanding Color Vision Deficiency
Human color vision depends on three types of cone cells in the retina, each sensitive to a different range of wavelengths: long (red/L-cones), medium (green/M-cones), and short (blue/S-cones). Color blindness occurs when one or more cone types are missing or dysfunctional. The severity ranges from mild anomalous trichromacy (reduced sensitivity) to complete dichromacy (absence of one cone type) or monochromacy (absence of all color vision).
Types of Color Blindness
Protanopia is the absence of red (L-cone) photoreceptors. People with protanopia cannot distinguish red from green and see reds as very dark — a red traffic light may appear nearly black. Red-orange safety colors can be dangerously invisible. This affects approximately 1% of males.
Deuteranopia is the absence of green (M-cone) photoreceptors. It is the most common form of color blindness, also affecting about 1% of males. While both protanopia and deuteranopia are classified as "red-green color blindness," the specific color confusions differ. Deuteranopia shifts greens toward brown and tan, making grass and foliage appear muddy.
Tritanopia is the absence of blue (S-cone) photoreceptors, sometimes called "blue-yellow color blindness." It is very rare (~0.003% of the population) and affects males and females equally since the gene is not on the X chromosome. Blues appear greenish, and yellows can look pink or violet.
Achromatopsia is complete color blindness — the person sees only in shades of gray. It is extremely rare and is often accompanied by light sensitivity and reduced visual acuity. This tool simulates achromatopsia by converting the color to its luminance value using the standard Rec. 709 coefficients.
How the Simulation Works
This simulator uses the Brettel, Vienot, and Mollon (1997) model, which is the gold standard for color blindness simulation in academic research and professional accessibility tools. Your input color is first converted from sRGB to linear RGB, then transformed through a matrix that projects the color onto the reduced color space experienced by someone with the specific deficiency. The result is converted back to sRGB for display. While no simulation can perfectly replicate individual experience, this model provides the most reliable approximation available.
Designing for Accessibility
The most important rule for color-accessible design is to never use color as the sole means of conveying information. Always pair colors with text labels, patterns, shapes, or icons. Use high-contrast combinations, avoid red-green pairings for critical distinctions, and test every design with a simulator. The Web Content Accessibility Guidelines (WCAG) 2.1 require a minimum contrast ratio of 4.5:1 for normal text and 3:1 for large text — requirements that benefit all users, not just those with color vision deficiency.