Colour blindness simulator
See a colour the way about one man in twelve does.
Protanopia — no red cones (about 1% of men)
Deuteranopia — no green cones (about 1% of men)
Tritanopia — no blue cones (rare, affects both sexes equally)
Achromatopsia — no colour at all (very rare)
About one man in twelve cannot tell red from green the way the rest of the population does, which is enough that a red error message and a green success message are, for them, the same message. This shows a colour through the four kinds of colour deficiency, using the Machado matrices applied to linear light rather than a crude filter.
How to use it
- Enter the colour.
- Compare the four simulations.
- If two of your colours converge, add a shape or a label.
Why use this tool
Completely private
Everything runs inside your browser. Your files and text are never sent to a server.
Free, with no limits
No sign-up, no watermarks and no cap on how many times you can use it.
Instant results
There is no upload or queue to wait for, so results appear as fast as your device can work.
Works on any device
Runs in any modern browser on phone, tablet or desktop. Nothing to install.
Frequently asked questions
- How accurate is this?
- It uses the Machado, Oliveira and Fernandes model from 2009, the same one browsers and design tools use, applied in linear light rather than to the sRGB values directly. It is a good approximation, not the experience itself.
- What should I do if two colours look the same?
- Do not rely on the colour alone. Add an icon, a label, a pattern or a difference in lightness. Anything that survives the colour being removed entirely will survive every kind of deficiency.
- Which kind matters most?
- Deuteranopia, by a wide margin: it is the most common, and it is the one that collapses red and green. Tritanopia is rare but affects women as often as men, unlike the red-green kinds.