Free Colour Blind Test
Take a free colour blind test online in about 2 minutes, with no sign-up and no email. Look at 13 circles of coloured dots and say which number you can see. Each circle tests one kind of colour-sensing cell in your eyes (red, green or blue) at four strengths, so you get a score for each one, the likely type of colour blindness and how strong it is.
- Free, no sign-up
- Red, green and blue scores
- No timer
- Shapes version for children
Before you start
- Turn off night mode, Night Shift, True Tone or any blue-light filter, and any colour filters.
- Turn your screen brightness up and avoid strong light shining on the screen.
- Keep your glasses on if you wear them, but take off any tinted or colour-correcting glasses.
This is a screening test, not a diagnosis. Screens show colours differently, so if you’re worried, ask an optician for a colour vision test.
What number can you see?
No timer: take as long as you need. On a keyboard, type the number and press Enter.
Your colour vision result
No sign of colour blindness
You didn’t see the first plate, which almost everyone can see, so this result may not be reliable. Check the tips above and try again.
Each score is how many of the four figures for that cone you saw, from faint (hardest) to strong. 75–100% is normal; on blue, 50% can be normal too, especially from middle age.
That’s your full result, free. No email, no glasses to sell you, nothing to pay.
How people with colour blindness see colours
The same picture, normal and as it looks with full-strength colour blindness. Milder types sit in between.
How to take the colour blind test
- Set up your screen. Turn off night mode and blue-light filters and turn the brightness up.
- Choose numbers or shapes. The shapes version is for young children or anyone who’d rather not read numbers.
- Look at each circle of dots. Type the number you can see, or pick the shape. If you can’t see anything, say so: that is a useful answer, not a wrong one.
- Get your result. After 13 plates you see a score for your red, green and blue cones, the likely type of colour blindness and how strong it is.
- See it for yourself. Compare everyday colours as people with each type of colour blindness see them, and share the test with friends.
Altto colour blind test: quick facts
A free online colour vision screening test for red-green and blue-yellow colour blindness, on a phone, tablet or computer.
Updated
- Price
- Free, with no sign-up and no email. Nothing to buy.
- Length
- About 2 minutes: 13 plates, with no timer.
- What it tests
- Each of your three kinds of cone (red, green and blue) separately, at four strengths, plus one warm-up plate everyone should see.
- Your result
- A score for each cone, the likely type (protan, deutan, red-green or tritan) and how strong it is (mild, moderate or strong).
- Versions
- Numbers, or shapes (circle, square, triangle, star) for children.
- Plates
- Drawn fresh for every test by your browser, so they can’t be learned or looked up.
- Accuracy
- A screening test. Your screen’s colours and settings affect it, so only an optician can confirm colour blindness.
- Privacy
- Runs in your browser. Your answers and result are never uploaded; your last result is saved only on your device.
How this colour blind test works
Your eyes have three kinds of colour-sensing cells called cones: L cones (most sensitive to red light), M cones (green) and S cones (blue). Colour blindness usually means one kind is missing or works differently.
Each plate hides a number made of dots that differ from the background in what one kind of cone sees, and nothing else. Every dot also gets a random brightness and random changes that the other two kinds of cone pick up, so there is no other clue. If that one kind of cone is weak or missing, the number disappears into the background. This is called cone isolation, the same idea used by newer tests that score each cone, rather than the fixed Ishihara plates first printed in 1917.
There are four plates for each kind of cone, from faint to strong. Missing only the faint ones points to mild colour blindness; missing them all points to a strong type. Because the plates are drawn fresh each time, you can take the test again and get new numbers.
Types of colour blindness
| Type | Cone affected | What it’s like |
|---|---|---|
| Deutan (deuteranomaly, deuteranopia) | Green (M) | The most common type. Greens, yellows, oranges and reds can be hard to tell apart. |
| Protan (protanomaly, protanopia) | Red (L) | Reds look darker and can be confused with greens, browns and black. |
| Tritan (tritanomaly, tritanopia) | Blue (S) | Rare. Blues and greens, and yellows and pinks, can be confused. |
| Achromatopsia | All | Very rare. Little or no colour seen at all, often with sensitivity to light. |
How common is colour blindness?
About 1 in 12 men and 1 in 200 women have some colour vision deficiency, most often red-green, which is passed down through families on the X chromosome. That’s roughly one child in every school class. Colour vision can also change later in life because of eye conditions such as glaucoma, other conditions such as diabetes or multiple sclerosis, an injury or some medicines.
Can colour blindness be cured?
There is no treatment for inherited colour blindness, and most people adapt well. Tinted lenses can change how some colours look to some people, but they don’t restore normal colour vision, and they shouldn’t be worn while taking a colour vision test. If colour vision changes because of another condition or a medicine, treating that may help.
Sources
- Colour vision deficiency (colour blindness) (NHS): causes, how opticians test it (Ishihara and colour arrangement tests), that colour testing isn’t part of a routine NHS eye test, and that inherited colour blindness has no treatment.
- Colour blindness statistically affects every male football team (City, University of London): about 1 in 12 men and 1 in 200 women.
- Viénot, Brettel and Mollon (1999), “Digital video colourmaps for checking the legibility of displays by dichromats” (Color Research and Application): the colour maths used to draw the plates. Machado, Oliveira and Fernandes (2009), “A physiologically-based model for simulation of color vision deficiency”: the “how they see it” pictures.
Frequently asked questions
Is this colour blind test free?
How accurate is an online colour blind test?
How does this test work?
What do my red, green and blue scores mean?
What are the types of colour blindness?
How common is colour blindness?
Is this an Ishihara test?
Can children take the test?
Does a normal NHS eye test check colour vision?
Can colour blindness be cured?
My colour vision has changed. What should I do?
Why can’t I see the numbers on the blue plates?
Is anything stored or uploaded?
Can I take the test again?
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