Color blindness simulator
See a palette as someone with deuteranopia, protanopia or tritanopia would.
Normal vision
Protanopia
Red-blind — about 1% of men
Deuteranopia
Green-blind — about 1% of men, the most common form
Tritanopia
Blue-blind — rare, about 0.01% of people, affects sexes equally
Achromatopsia
Total colour blindness — very rare
Colours that become hard to distinguish
| Simulation | Pair | Contrast between them |
|---|---|---|
| Protanopia | #2f6f43 #1f6fb8 | 1.06 : 1 |
| Protanopia | #b3261e #8a6100 | 1.04 : 1 |
| Protanopia | #b3261e #6b6b65 | 1.11 : 1 |
| Protanopia | #8a6100 #6b6b65 | 1.15 : 1 |
| Deuteranopia | #2f6f43 #1f6fb8 | 1.05 : 1 |
| Deuteranopia | #b3261e #8a6100 | 1.13 : 1 |
| Deuteranopia | #8a6100 #6b6b65 | 1.23 : 1 |
| Tritanopia | #2f6f43 #b3261e | 1.15 : 1 |
| Tritanopia | #2f6f43 #8a6100 | 1.08 : 1 |
| Tritanopia | #b3261e #8a6100 | 1.24 : 1 |
| Tritanopia | #b3261e #6b6b65 | 1.27 : 1 |
| Achromatopsia | #2f6f43 #b3261e | 1.13 : 1 |
| Achromatopsia | #2f6f43 #8a6100 | 1.18 : 1 |
| Achromatopsia | #2f6f43 #1f6fb8 | 1.13 : 1 |
| Achromatopsia | #b3261e #1f6fb8 | 1.28 : 1 |
| Achromatopsia | #8a6100 #1f6fb8 | 1.05 : 1 |
| Achromatopsia | #8a6100 #6b6b65 | 1.13 : 1 |
| Achromatopsia | #1f6fb8 #6b6b65 | 1.18 : 1 |
How it works
Around 8% of men and 0.5% of women of northern European descent have some form of colour vision deficiency. The most common types affect the red-green axis, which is precisely the axis most interfaces use for “good” and “bad”.
What the simulations show
- Protanopia
- The long-wavelength (red) cones are missing. Reds appear dark and shift toward brown.
- Deuteranopia
- The medium-wavelength (green) cones are missing. The most common form; red and green converge on yellow-brown.
- Tritanopia
- The short-wavelength (blue) cones are missing. Rare, and affects blue-yellow rather than red-green.
- Achromatopsia
- No colour discrimination at all. Extremely rare, and the strictest test of whether your design works on luminance alone.
Never rely on hue alone
If red means error and green means success, someone with deuteranopia sees two similar yellow-browns. Pair colour with a second signal every time — an icon, a label, a pattern, a position. This is WCAG success criterion 1.4.1, “Use of Color”.
Design for luminance
Colours that differ in lightness stay distinguishable under every deficiency. A quick check: view your palette in greyscale — the achromatopsia row above does exactly that. If the swatches merge there, they will be ambiguous for someone.
These are approximations
The simulation uses linear matrix transforms, which reproduce the broad effect but not the full physiology — and they model the complete absence of a cone type (dichromacy) rather than the more common reduced sensitivity (anomalous trichromacy). Use them to catch obvious problems, not to certify a design.