Color Blindness Simulator
Paste a palette and see it as people with protanopia, deuteranopia, tritanopia and achromatopsia would. Pairs that become hard to tell apart are flagged automatically.
The main types of color vision deficiency
| Type | Affected cones | Typical confusions | Roughly how common |
|---|---|---|---|
| Deuteranomaly / deuteranopia | Green (M) | Red-green, brown-green | About 6% of men in total |
| Protanomaly / protanopia | Red (L) | Red-green; reds look darker | About 2% of men in total |
| Tritanomaly / tritanopia | Blue (S) | Blue-green, yellow-pink | Rare (about 1 in 10,000) |
| Achromatopsia | All cones | Sees only lightness | Very rare (about 1 in 30,000) |
Overall, about 8% of men and 0.5% of women of Northern European ancestry have a red-green deficiency. The simulator shows the strongest (dichromatic) form, so if your palette works here it will also work for the milder forms.
How to fix colors that merge
- Change lightness, not just hue. Two colors with very different lightness stay distinguishable for every type of color vision. The achromatopsia row shows lightness alone.
- Never rely on color alone. WCAG 1.4.1 (Level A) requires another cue: a label, icon, pattern or position.
- Prefer blue/orange over red/green for status pairs and two-series charts.
- Check text contrast separately with the contrast checker; simulation does not replace the 4.5:1 rule.
More practical patterns are in our guide to designing for color blindness.
Frequently asked questions
How accurate is this simulation?
It uses the Machado, Oliveira and Fernandes (2009) model at full severity, which is the same family of models used by browser developer tools. It is a good approximation of dichromacy (protanopia, deuteranopia, tritanopia); real people vary, and milder "anomalous" forms are far more common.
Which type should I test first?
Deuteranopia and protanopia (red-green) cover the large majority of people with color vision deficiency, so test those first. Tritanopia is rare but worth a quick check for blue/yellow distinctions.
What does "hard to tell apart" mean?
We compare every pair of your colors after simulation using the CIE76 color difference (ΔE). Pairs with ΔE below 10 are flagged: they may still be distinguishable side by side, but should not be the only way to separate two categories.
Model: G. M. Machado, M. M. Oliveira and L. A. F. Fernandes, "A Physiologically-based Model for Simulation of Color Vision Deficiency", IEEE TVCG, 2009 (severity 1.0, applied to linearized sRGB).