Color Blindness Test
A colour vision screening covering red-green, blue-yellow and total colour blindness — an indication only, not a diagnosis.
For each plate, type the number you see. If you can't make out any number, press “Can't tell” instead of guessing. Use a properly-lit screen at full brightness.
1. Red–green plates
Screens the common protan/deutan (red-green) deficiencies.
2. Blue–yellow plates
Screens the rare tritan (blue-yellow) deficiency.
3. Total color blindness plates
A number in color on a gray background — only someone with no color vision at all would see nothing.
4. Color arrangement test
Click a swatch, then click another to swap them, until the colors run smoothly from left to right. The first swatch is fixed as the starting point.
5. Color matching test
Adjust the left color until it matches the yellow reference on the right. Most people match it with roughly equal red and green.
6. Color-blindness simulator
A rough simulation of how the same colors — a spectrum, swatches, and a traffic light — look with each type of color blindness.
Simulation uses standard dichromat approximations; individual perception varies.
Plate results
⚠️ This is an informal screening test, not a medical diagnosis, and it cannot identify the exact subtype of a deficiency (e.g. protan vs deutan). Screen calibration, brightness, and lighting all affect the result. For a proper assessment, see an eye-care professional.
How to use
- Use a calibrated screen at normal brightness if you can.
- View in even lighting, without glare.
- Work through the plates without straining.
- See an optometrist for anything the result raises.
Frequently asked questions
Is this a real diagnostic test?
No. Clinical colour vision testing uses printed plates under standardised lighting, or specialised instruments, precisely because screens vary enormously in colour reproduction. A browser test can suggest something worth checking; it cannot diagnose, and a poor result may be your display.
How common is colour vision deficiency?
Roughly one in twelve men and one in two hundred women of northern European descent. The large difference is because the most common forms are carried on the X chromosome, so men have no second copy to compensate.
What are the different types?
Red-green deficiencies — protan and deutan — are by far the most common. Blue-yellow deficiency is rare, and complete absence of colour vision rarer still. The everyday label 'colour blind' usually describes reduced discrimination rather than seeing no colour at all.
Can it be corrected?
Not cured. Filtering glasses can increase the separation between confusable colours for some people and do not restore normal vision, and results vary considerably between individuals. They are worth trying and worth being sceptical of the marketing around.
Why does this matter for design?
Because relying on colour alone to convey information excludes a substantial number of people. Adding a shape, label, pattern or text alternative costs almost nothing and makes the design work for everyone — which is why accessibility guidance treats it as a requirement rather than a nicety.
When should I see a professional?
If the result surprises you, if colour perception has changed recently, or if it affects work or driving. Acquired changes in colour vision can indicate other conditions, which is why a sudden change is worth a proper examination. Nothing here is medical advice.
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