Color Blindness Simulator
See how colors and images look to people with different types of color blindness
Normal Vision
Normal
About the Colour Blindness Simulator
This color blind simulator shows how your colours appear to people with deuteranopia, protanopia and tritanopia alongside normal vision. It catches the most common accessibility failure, where a red-and-green status indicator collapses into two nearly identical muddy tones for around 8% of men.
A color blind simulator answers a question you cannot check by eye: does this still work for someone who does not see colour the way I do? Around 8% of men and 0.5% of women have some colour vision deficiency, which is a large share of any audience.
The three simulated types cover most of it. Deuteranopia — reduced green sensitivity — is the most common, and it is what makes red and green nearly identical. Protanopia affects red sensitivity with a similar effect on that pairing. Tritanopia, affecting blue and yellow, is rarer.
The recurring failure is meaning carried by colour alone: green for success and red for error, a red line and a green line on a chart, or required fields marked only in red. The fix is not avoiding colour but adding a second signal — an icon, a label, a different line style — so colour is reinforcement rather than the only cue.
How to use the Colour Blindness Simulator
- Enter your colours. Add the palette or the specific pair you want to check.
- Switch simulation types. Compare deuteranopia, protanopia and tritanopia against normal vision.
- Look for collapsed pairs. Find colours that become indistinguishable from each other.
- Add a second signal. Where meaning relied on colour, add an icon, label or pattern too.
Colour Blindness Simulator features
- Six simulations: protanopia, deuteranopia, tritanopia, achromatopsia, protanomaly and deuteranomaly
- Normal vision shown alongside for comparison
- Upload a screenshot, mockup or design to test
- Colour matrix filters applied in the browser
- Download the simulated image
- The image is processed locally and never uploaded
Frequently asked questions
Which types of colour blindness are simulated?
Protanopia and deuteranopia — red and green deficiency, the common ones — plus tritanopia, achromatopsia, and the milder protanomaly and deuteranomaly. Normal vision is shown next to them so the difference is visible rather than imagined.
How does the simulation work?
Each pixel is passed through a colour matrix that models how a given deficiency shifts the response of the affected cone type. It is an approximation of a subjective experience, not a measurement, but it is the standard approach and it reliably surfaces the failures that matter.
What should I test first?
Anything where colour alone carries meaning: red and green status indicators, chart series distinguished only by hue, required-field highlighting, and links identified by colour without an underline. Red-on-green is the classic failure.
How do I fix a problem it reveals?
Add a second signal so colour is never the only cue — an icon, a label, a pattern, a shape. Increasing lightness contrast between the colours also helps, because deficiency affects hue discrimination far more than it affects brightness.
Does it check WCAG contrast ratios?
No. This simulates colour perception rather than measuring contrast, so pair it with a dedicated contrast checker — the two catch different problems and you need both.
How many people does this affect?
Roughly 8% of men and 0.5% of women have some form of colour vision deficiency, most commonly red-green. On any site with meaningful traffic that is a substantial group, and very few of them will report the problem.