How accurate is an online colour blindness test?

It is good at flagging a strong red-green deficiency and unreliable for anything mild. Screen calibration, ambient light, and blue-light filters all move the colours. Use it as a prompt to get properly tested, never as a conclusion.

I got everything right but I still confuse some colours. Why?

Ishihara plates target red-green confusion specifically and are insensitive to mild or blue-yellow deficiency. They also cannot detect the acquired forms that develop with eye disease. Normal plates plus real-world difficulty is a good reason for a clinical test.

Can colour blindness be corrected?

No. Tinted lenses can increase the contrast between colours that you confuse, which some people find genuinely useful, but they do not restore the missing cone response. The underlying deficiency is unchanged.

Why do more men have it than women?

The genes for red and green photopigments sit on the X chromosome. A man has one X, so a single affected copy produces the deficiency. A woman has two, and the second copy usually compensates. This is why red-green deficiency affects about 8 percent of men and about 0.5 percent of women.

What are the dots in a colour blindness test for?

They stop you solving the plate by brightness. Every dot is randomised in size and lightness, so a figure that differs from its background only in hue cannot be found by looking for a lighter or darker shape. Someone who cannot separate the two hues has no other cue available.

At what age can a child take this test?

Numeric plates need confident digit reading, so roughly school age at the earliest. Clinical versions for younger children use shapes or winding paths instead of numbers. Deficiency is present from birth and does not change, so there is nothing lost by waiting until a child can do the shape version properly.

Does failing this test disqualify me from a job?

Not by itself, and not from this page in any case. Occupational standards are assessed in person, and many accept a pass on a secondary test such as a lantern or an arrangement test after a failed plate screening, because those distinguish mild deficiency from severe. Requirements vary by country, employer, and role.

Hardware diagnostic · no ranking

Color Blindness Test

Fourteen plates. Type what you see, or say that you see nothing.

Loading the test

Before you start

Run the test and your reading appears here.

Why this reports a type instead of a percentile

Colour vision deficiency is not a spectrum that everyone sits somewhere on. Around 92 percent of people have normal colour vision and get essentially every plate right. Reporting your rank in that population would tell you nothing: you would either be at the top with everyone else or far outside it.

What is worth knowing is which plates you missed. Red-green deficiency and blue-yellow deficiency produce different miss patterns, and the pattern is the diagnostic signal. So this test reports the type the errors point to, and it says plainly when the pattern is not clear enough to call.

The three patterns this screens for

Protan, a red weakness. Reds appear darker and duller, and red against black can vanish entirely. Affects roughly 1 percent of men.

Deutan, a green weakness. By far the most common form, around 5 percent of men. Reds and greens both drift toward a muddy yellow-brown. Many people with mild deutan deficiency reach adulthood without knowing.

Tritan, a blue-yellow weakness. Rare, roughly 1 in 10,000, and unlike the other two it is not sex-linked. It can also be acquired later in life through eye disease or medication, which makes a new tritan result more worth following up than a lifelong red-green one.

What a screening test cannot do

Ishihara-style plates were designed for print under standard illumination. Your screen is not that. Panel calibration, brightness, colour profile, ambient light, and any night-shift or blue-light filter all shift the colours away from the intended values, and every one of those shifts can create a false result in either direction.

A screening test also cannot grade severity. Clinical assessment uses an anomaloscope or an arrangement test like the Farnsworth D-15 to establish how strong a deficiency is, which is the part that matters for occupational requirements.

Turn off any colour filter, set brightness to normal, and view in even lighting. If the result surprises you, repeat it on a different screen before believing it.

Where these plates came from

The pattern of coloured dots is an Ishihara plate, designed by Shinobu Ishihara and first published in 1917. The design solves a specific problem: it hides the figure from anyone relying on brightness rather than hue. Every dot is randomised in size and lightness, so a numeral that differs from its background only in colour cannot be found by looking for a lighter or darker shape. Someone who cannot separate the two hues has nothing left to go on.

A full set contains several kinds of plate. Transformation plates show one number to normal viewers and a different number to a deficient viewer. Vanishing plates show a figure only to normal viewers. Hidden-digit plates do the opposite and are visible only to deficient viewers, which is why claiming to see a number that is not there is itself a signal. A short screening set draws from these categories rather than repeating one type.

The design has been in continuous clinical use for over a century, which is unusual, and its limits are equally well established: it screens for red-green deficiency well, detects blue-yellow poorly, and grades severity not at all.

Jobs that set a colour vision standard

Some occupations set colour vision requirements, most often those where a colour-coded signal carries safety information: commercial piloting, some rail and maritime roles, parts of the armed forces, and certain electrical work. Requirements differ by country, by employer, and by specific role, and some accept a pass on a secondary test even after a failed plate screening.

That second point is the one worth knowing. A failed Ishihara screening is frequently not the end of the matter. Lantern tests and arrangement tests such as the Farnsworth D-15 distinguish mild deficiency from severe, and several standards care about severity rather than presence. People who assume a screening result disqualifies them sometimes never take the test that would have passed them.

Nothing on this page carries any weight for those purposes. Occupational assessment is done in person, with calibrated plates or an anomaloscope, under controlled lighting.

Testing a child

Colour vision deficiency is present from birth and does not change, so there is no age at which it develops or improves. Children are usually identified in the early school years, often by a teacher noticing colouring or sorting that looks odd rather than by any complaint, because a child with no other experience has no reason to think their colours differ from anyone else.

Numeric plates need a child who reads digits confidently, which makes this page unsuitable below roughly school age. Clinical versions for younger children replace the numbers with shapes or winding paths to trace. If a young child is being screened, that is the version to ask for.

The practical reason to find out early is educational rather than medical. Nothing about the deficiency can be treated, but a great deal of teaching material is colour-coded, and a child who is quietly guessing at colour-coded work benefits from a teacher who knows.

Questions

How accurate is an online colour blindness test?: It is good at flagging a strong red-green deficiency and unreliable for anything mild. Screen calibration, ambient light, and blue-light filters all move the colours. Use it as a prompt to get properly tested, never as a conclusion.
I got everything right but I still confuse some colours. Why?: Ishihara plates target red-green confusion specifically and are insensitive to mild or blue-yellow deficiency. They also cannot detect the acquired forms that develop with eye disease. Normal plates plus real-world difficulty is a good reason for a clinical test.
Can colour blindness be corrected?: No. Tinted lenses can increase the contrast between colours that you confuse, which some people find genuinely useful, but they do not restore the missing cone response. The underlying deficiency is unchanged.
Why do more men have it than women?: The genes for red and green photopigments sit on the X chromosome. A man has one X, so a single affected copy produces the deficiency. A woman has two, and the second copy usually compensates. This is why red-green deficiency affects about 8 percent of men and about 0.5 percent of women.
What are the dots in a colour blindness test for?: They stop you solving the plate by brightness. Every dot is randomised in size and lightness, so a figure that differs from its background only in hue cannot be found by looking for a lighter or darker shape. Someone who cannot separate the two hues has no other cue available.
At what age can a child take this test?: Numeric plates need confident digit reading, so roughly school age at the earliest. Clinical versions for younger children use shapes or winding paths instead of numbers. Deficiency is present from birth and does not change, so there is nothing lost by waiting until a child can do the shape version properly.
Does failing this test disqualify me from a job?: Not by itself, and not from this page in any case. Occupational standards are assessed in person, and many accept a pass on a secondary test such as a lantern or an arrangement test after a failed plate screening, because those distinguish mild deficiency from severe. Requirements vary by country, employer, and role.

Where does the curve behind this page come from, and when does it get thrown away? The methodology page names the source of every reference distribution on the site, the sample size behind it, and the point at which real results replace it.