About the Color Blindness Simulator
About one in twelve men and one in two hundred women have some form of colour vision deficiency, so designs that rely only on colour can be hard or impossible to read for them. This simulator shows you how a picture looks to people with the most common types: deuteranopia and protanopia (red-green), tritanopia (blue-yellow), the milder weak-colour versions and complete colour blindness. Upload a screenshot, chart, logo or map, and see all the versions side by side. You can enlarge any of them and save it as a PNG. The simulation uses published colour transformation matrices and runs in your browser, so your designs stay private.
Updated October 2026
How to use the Color Blindness Simulator
- 1Drop a picture, a screenshot or a design.
- 2Look at the normal version and the seven simulations.
- 3Press Look closer on any type to enlarge it.
- 4Save any simulated picture as a PNG.
- 5Change the design if important parts become hard to tell apart.
What each type sees
In deuteranopia and protanopia, reds, greens, oranges and browns shift towards yellows and browns and become hard to tell apart. Protanopia also makes red look darker. In tritanopia, blues and greens look similar and yellows look pale or pink. In achromatopsia, only light and dark are seen.
The weak versions are milder and much more common. Deuteranomaly alone affects roughly 5 percent of men, so a design that works for the milder types is helping a lot of people.
Design checks
- Charts: use different shapes, labels or line styles besides colour.
- Status colours: pair red and green with icons or words.
- Maps: choose palettes made for colour blindness, with different lightness.
- Links: underline them instead of relying on colour.
- Forms: mark errors with text and an icon, not only a red outline.
- Test the grey version: if it still works, colour is not carrying the meaning alone.
Related tools
Check text readability with the Color Contrast Checker, turn a photo into grey tones with the Black and White Image tool and find the exact colours of a design with the Image Color Picker. To name colours try the Color Name Finder, and to change formats use the Color Converter. Good accessibility helps everyone.
Features
- Deuteranopia, protanopia and tritanopia
- Weak-colour versions: deuteranomaly, protanomaly, tritanomaly
- Complete colour blindness (achromatopsia)
- All types side by side
- Look closer and save as PNG
- Based on published research matrices
- Private, runs in your browser
Frequently asked questions
What are the types of colour blindness?
Red-green types (protan and deutan) are the most common, blue-yellow types (tritan) are rare and total colour blindness is very rare. Anomaly means the cone works but is weaker, and anopia means it does not work.
How accurate is a simulation?
It is a good approximation based on research models, but real vision varies from person to person and screens differ. Treat it as a guide and test with real people when you can.
How can I make a design more accessible?
Do not rely on colour alone. Add labels, patterns, icons or different lightness. Check the contrast between text and background and avoid red-green pairs for important information.
What picture should I upload?
Charts, maps, user interface screenshots and logos are the most useful. Photos work too but are mainly of interest for art and design.
Why does grey stay grey?
The simulations keep neutral colours as they are, since people with colour blindness see greys normally. Only colours that depend on the missing cone are changed.
Is my picture uploaded?
No. The simulation is done in your browser.
Does it replace a real vision test?
No. It does not test anyone's eyes. If you think you have colour vision problems, ask an optician.