Colour Blindness Test
Eight plates, about a minute. This is a screen, not a diagnosis — your screen’s colour rendering alone makes it unreliable as a clinical test.
What this test can and cannot tell you
It can suggest whether you may have a red-green colour vision deficiency. It cannot diagnose one. Ishihara plates were designed as printed cards under standard lighting, and every screen renders colour differently — brightness, colour profile, night mode and ambient light all shift the result. A proper assessment uses calibrated printed plates and, where it matters, an anomaloscope. Treat a poor result here as a reason to book an eye test, not as an answer.
Types of colour vision deficiency
| Type | Affects | Roughly how common |
|---|---|---|
| Deuteranomaly | Green cones shifted — greens look more red | ~5% of men |
| Protanomaly | Red cones shifted — reds look duller and darker | ~1% of men |
| Deuteranopia / protanopia | One cone type absent | ~1% of men each |
| Tritanomaly / tritanopia | Blue-yellow, not detected by these plates | Very rare, affects both sexes equally |
| Achromatopsia | No colour vision at all | About 1 in 30,000 |
Red-green deficiency is carried on the X chromosome, which is why it affects roughly 8% of men of northern European descent but only about 0.5% of women. This test screens for red-green types only.
If you do have it
It is a variation rather than a disease, it does not get worse, and most people manage without difficulty once they know.
- It affects some careers. Commercial piloting, some electrical work, parts of the armed forces and certain medical roles have colour vision requirements.
- Design for it, if you design. Never rely on colour alone to carry meaning — add labels, patterns or icons. Roughly one in twelve men cannot distinguish your red error state from your green success state.
- Phone tools help. Both iOS and Android have colour filters and a colour identifier that names what the camera sees.
- Tinted lenses are marketed heavily. They shift perception and can make some distinctions easier, but they do not restore normal colour vision, and evidence for real-world benefit is mixed.
How to use the Colour Blindness Test
- Set your screen to normal brightness and turn off any night or warmth filter.
- Press start, then answer each plate with your first impression.
- Read the breakdown afterwards — it shows what each plate was testing.
Frequently asked questions
Is this test accurate?
It is a screening indication, not a diagnosis. Screens are not colour-calibrated, so both false positives and false negatives are possible. An optometrist using printed plates is the reliable test.
Why does everyone see 12 on the first plate?
That plate is a control. It is designed to be readable regardless of colour vision, and it confirms the test is displaying at all. If you cannot read it, something is wrong with the display rather than your eyes.
How common is colour blindness?
Around 8% of men and 0.5% of women of northern European descent have some red-green deficiency. Rates are lower in other populations.
Can colour blindness be cured?
No. It is genetic and permanent. Tinted lenses can make certain distinctions easier for some people but do not restore normal colour vision.
Does this test blue-yellow deficiency?
No. Ishihara-style plates screen for red-green types. Blue-yellow deficiency is much rarer and needs different testing.
Are my answers stored?
No. Everything happens in your browser and nothing is recorded or transmitted.
Related tools
Last reviewed September 4, 2026. A screening indication only. Screen colours are not calibrated — a proper diagnosis needs an optometrist with printed plates.