How to Test for Color Blindness Online (Free)
Quick answer: To test for colour blindness online, view a series of Ishihara-style colour plates and report the number or shape you see in each. It gives a quick, free indication of red-green or blue-yellow deficiency — but only an eye doctor can give a clinical diagnosis.
Try it now: open the colour blindness test and read each plate in good, neutral lighting.
How the online test works
The test shows Ishihara-style plates — circles of coloured dots with a number or shape hidden inside using a contrasting colour. People with normal colour vision read the figure easily; those with a colour deficiency see a different number or none at all.
Types of colour blindness
Red-green deficiency is by far the most common and comes in two main forms, protan (red) and deutan (green). Blue-yellow deficiency (tritan) is much rarer, and complete colour blindness, where no colours are distinguished, is very rare.
How accurate is an online test?
Treat the result as an indication, not a diagnosis. Monitor calibration, brightness and room lighting all shift how colours appear on screen, so a clear result still warrants a proper exam. An optometrist uses calibrated plates and other tests to confirm the type and severity.
Can colour blindness be corrected?
There is no cure, but it is usually mild and manageable. Some people find specialised lenses help them distinguish certain colours, and apps and accessibility settings can label or adjust colours on devices.
Take the test
Run the colour blindness test to see how you do, and book an eye exam if the result or everyday colour confusion concerns you.
How Colour Blindness Testing Works
The most familiar colour vision test uses Ishihara plates — circles filled with coloured dots that contain a number or shape visible to people with normal colour vision but hard or impossible to read for those with a colour deficiency. By showing a series of these plates, a test can suggest whether you have a colour vision deficiency and hint at which type. Our colour blindness test works on this principle, presenting plates for you to identify. It's a quick, accessible screening you can do at home in a couple of minutes.
An Important Caveat
An online test is a screening tool, not a medical diagnosis. Screen results depend heavily on your display: brightness, colour calibration, blue-light filters and even ambient lighting can all skew how the plates appear, so a home test can give a false result in either direction. If a test suggests you may have a colour vision deficiency — or if you have practical reasons to know for sure, such as a job with colour requirements — see an optometrist or eye-care professional. They use calibrated plates and additional instruments under controlled conditions to give an accurate diagnosis and identify the exact type and severity. Treat an online result as a useful prompt to look into it further, not a final answer.
How to Take the Test Properly
- Use good, neutral lighting — avoid coloured light and harsh glare on the screen.
- Turn off blue-light filters and night-mode colour shifts, which distort the plates.
- Set your screen to normal brightness and view it straight on at a comfortable distance.
- Don't strain or guess — note what you genuinely see at a glance, since that's what the plates are designed to measure.
- Wear your usual glasses or contacts if you use them for screens.
What the Results Mean
Colour vision deficiency is more common than many realise — it affects roughly 1 in 12 men (about 8%) and around 1 in 200 women, the difference being down to how the condition is inherited. Most people with it have a partial deficiency rather than seeing no colour at all, and many go years without realising. The most common form is red-green deficiency. If your test points to a possible deficiency, our guide on the types of colour blindness explains what each kind means. Remember that colour blindness isn't an illness to be cured but a difference in colour perception, and most people with it adapt well in daily life.
Beyond Ishihara: Other Tests
Ishihara plates are the best-known screening, but eye-care professionals use other tests too, each suited to a different purpose. The Farnsworth D-15 asks you to arrange coloured caps in order, which reveals not just whether you have a deficiency but how it's organised and how severe it is. The anomaloscope is considered the gold standard: you match a colour by mixing red and green light, and it precisely identifies and grades red-green deficiencies. These instruments are used under controlled lighting with calibrated colours, which is why a professional assessment is far more reliable than any home screening. Early testing matters especially for children — knowing about a colour deficiency helps with schoolwork that relies on colour coding, and with choosing hobbies and, later, careers where colour vision is required. If you or your child may have a deficiency, an optometrist can confirm it and explain exactly what it means in practice.
Frequently Asked Questions
How do I test for colour blindness?
Use an Ishihara-style plate test, like the colour blindness test, which shows circles of coloured dots containing numbers that are hard to read with a colour deficiency. Take it in good neutral lighting with blue-light filters off. It's a screening, not a diagnosis.
Is an online colour blindness test accurate?
It's a useful screening, but not a diagnosis. Screen brightness, calibration, blue-light filters and lighting all affect the result. For an accurate answer, especially for work requirements, see an optometrist who uses calibrated plates under controlled conditions.
How common is colour blindness?
It affects roughly 1 in 12 men (about 8%) and around 1 in 200 women. The difference is due to how it's inherited. Most people have a partial red-green deficiency rather than seeing no colour at all, and many don't realise they have it.
Should I see a doctor about colour blindness?
If a home test suggests a deficiency, or you need certainty for a job with colour requirements, see an optometrist or eye-care professional. They use calibrated tests to confirm the exact type and severity that an online screening can only hint at.
Can colour blindness be cured?
No, inherited colour blindness can't be cured — it's a lifelong difference in how the eye perceives colour, not an illness. Special tinted glasses help some people distinguish certain colours better, and apps and good design make colour cues easier to navigate.
Can colour blindness develop later in life?
Yes. While most colour blindness is inherited and present from birth, colour vision can change later through eye diseases, certain medications, diabetes, or ageing. A noticeable change in colour perception as an adult is worth having an eye doctor check.
At what age can colour blindness be tested?
Children can usually be screened once they can reliably name numbers or shapes, often around four or five, with picture-based versions for younger ones. Early detection helps with colour-coded schoolwork and choosing hobbies, so it is worth checking if it runs in the family.
Why can I not read the number in some test plates?
If you cannot see a number that people with normal colour vision can, it may point to a colour deficiency in the range that plate tests. Screen calibration and lighting can also cause it, which is why a professional test is needed to be sure.