Free color blindness test online
This color blindness test is a quick screening for color vision differences that runs in your browser, for free, with no sign-up. It checks three kinds of color vision: the two red–green kinds, called protan and deutan, and the blue–yellow kind, called tritan. The quick screen takes about two minutes; the full test takes a few minutes more and finds the faintest difference you see on each kind of plate. Your results stay on your device.
It’s a screening for curiosity, not a medical test. A screen can’t show colors as exactly as a printed, professionally lit test, so the result is a pointer, never a diagnosis.
How to take the test
- Go through the list above the test: night mode and blue-light filters off, brightness high, no tinted glasses, an arm’s length from the screen. Then tick the box.
- Choose the quick screen or the full test, and press Start.
- A practice plate shows a ring of darker dots. Press the arrow for the side its gap is on.
- Then the test plates. Some are clear and some are faint. If you can’t find the ring, press “Can’t see it” rather than guess.
How the plates work
Each plate is a circle of dots of different sizes. Some of the dots form a ring with a gap, like the letter C, and the gap points up, down, left or right. A ring with a gap is used in eye tests because it reads the same in any language: there are no numbers or letters to know.
The eye sees color with three kinds of cone cell, sensitive to long, medium and short wavelengths of light, roughly red, green and blue. The ring on each plate differs from the dots around it in a way that only one kind of cone responds to, while the other two respond exactly as they do to the dots around it. Someone whose cones of that kind work differently finds that ring hard or impossible to see; to everyone else it shows as a colored ring. Every dot also gets a random brightness, so the ring can’t be found by brightness alone.
Some plates are checks: their ring is much darker than the dots around it, so anyone can see it. If two or more of them are missed, the test gives no result, because something else, such as a screen setting or a moment’s distraction, affected it.
The plates are generated on your device for each test. They are not the Ishihara plates, the well-known printed plates with numbers made of colored dots. Those were designed for their printing inks and particular lighting, and copies on a screen don’t show them as intended.
Quick screen or full test
The quick screen shows 15 plates: four of each kind, two fainter and two stronger, plus three checks. A kind of plate counts as seen if you get at least three of its four right. It takes about two minutes.
The full test shows the three kinds of plate in a random mix. Each kind gets fainter after two right answers in a row and stronger after a wrong one or “Can’t see it”, until it settles on the faintest difference you see reliably. One plate in six is a check. It takes 40 to 110 plates, about 3 to 8 minutes. If one kind of red–green plate is clearly harder for you than the other, the result says which type it leans to; if the two are close, it says so.
Types of color vision difference
Red–green differences are the most common. In the protan type, the long-wavelength (red-sensitive) cones work differently or are missing; in the deutan type, the medium-wavelength (green-sensitive) cones do. Either way, some reds, greens, browns and oranges are harder to tell apart. Red–green differences are usually inherited and present from birth, and they are much more common in men than in women: in a review of studies worldwide, about 8% of men and 0.4% of women of European descent had one, with lower rates in many other populations (J. Birch, Worldwide prevalence of red-green color deficiency, Journal of the Optical Society of America A, 2012).
Blue–yellow differences, the tritan type, involve the short-wavelength (blue-sensitive) cones. Inherited ones are much rarer than red–green ones. Blue and green, or yellow and pink, can be harder to tell apart.
Many people with a color vision difference see colors, just not the same way as most people, and some don’t know until they’re tested. Color vision can also change later in life. A change you notice is a reason to see an eye doctor, whatever any online test says.
Screens and lighting
A screen isn’t a calibrated test chart. Night modes and blue-light filters (Night Shift, True Tone, f.lux), color settings, low brightness, the angle you look from and the light in the room all change the colors you see. A warm filter, for example, can hide the blue–yellow plates for anyone. That’s why the test asks you to check your settings first, includes the check plates, and words its result cautiously.
What your result means
The quick screen shows each kind of plate as seen or not seen, and one of these readings: consistent with typical color vision; suggests a red–green color vision difference; suggests a blue–yellow color vision difference; or both. The full test adds, for each kind, the faintest difference you saw, as a change in one kind of cone’s response. Smaller means fainter. It isn’t a degree of color blindness, and it depends on your screen.
A reading other than typical means your answers on this screen looked like those of someone with that color vision difference. It doesn’t mean you have one. An optometrist or eye doctor can test your color vision properly, with tests made for the purpose, in controlled light.
Your results
Results are saved only in this browser, and nothing is sent anywhere. Your past results are listed under the test, and “Delete my results” removes them all.
Keyboard
| Arrow keys | The side the ring’s gap is on |
|---|---|
| Space | Can’t see it |
| Tab, Enter | Reach and press Start, Try again or Restart |
Questions
Can this test tell me if I’m color blind?
No. It can suggest whether your answers look like those of someone with a color vision difference, on your screen, today. Only an optometrist or eye doctor can tell you, with tests made for the purpose.
Is this the Ishihara test?
No. The Ishihara test is a book of printed plates with numbers made of colored dots. These plates are generated on your device, use a ring with a gap instead of numbers, and pick their colors from how the three kinds of cone cell respond, a method used in research tests of color vision.
What do protan, deutan and tritan mean?
They name the kind of cone cell involved: protan the long-wavelength (red-sensitive) cones, deutan the medium-wavelength (green-sensitive) ones and tritan the short-wavelength (blue-sensitive) ones. Protan and deutan are the two red–green kinds; tritan is the blue–yellow kind.
Why did I get a different result on another device?
Screens differ in their colors, and settings and room light change them further. The test works out its colors for a standard screen, and no browser can tell how far yours is from it. Compare results from the same device, with the same settings.
I couldn’t see the blue–yellow plates. Why?
The most common reason is a screen setting that warms the colors, such as night mode, Night Shift or a blue-light filter. Turn it off, check the list above the test and try again. If the result stays the same, an eye doctor can check.
Can I take it with glasses or contact lenses?
Yes, wear the ones you normally use. Only tinted glasses, sunglasses and lenses sold to help with color vision change the result.
Can children take it?
The plates use no numbers or letters, only which way a gap points, so a child who can follow the instructions can take it with an adult. It doesn’t replace a check by an eye doctor or at school.
Where are my results kept?
Only in this browser. Nothing is sent anywhere. “Delete my results” removes them, and so does clearing your browser’s site data.
This is a screening for curiosity, not a medical test. Screens, settings and lighting affect results. For a diagnosis, see an optometrist or eye doctor.
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