Color Blind Test

By Murat Şahin · Updated November 12, 2026 · How we test

How the plates work

Your retina has three kinds of cone cells. L cones respond most to long-wave (reddish) light, M cones to medium-wave (greenish) light and S cones to short-wave (bluish) light. Color blindness usually means one cone type is missing or has its sensitivity shifted. That is a different question from how finely you can tell two similar shades apart, which the hue test measures.

Each plate in this test is a circle of dots with a number inside. The number and the background are mixed so that they differ for only one cone type. If your L, M and S cones all work in the typical way, the number pops out. If the cone type a plate targets is weak or missing, the number melts into the background. The colors are computed with the cone model of Viénot, Brettel and Mollon (1999), and every dot gets a random brightness so you cannot find the number by lightness alone. How faint a difference in lightness you can see is what the contrast sensitivity test measures.

There are 15 plates:

• Plate 1 is a high-contrast control. Almost everyone reads it. If you miss it, the run is not scored.
• 5 red plates (L cone) and 5 green plates (M cone), each step with less cone contrast than the one before.
• 4 blue plates (S cone), also getting harder.

The order after plate 1 is shuffled and the numbers are random, so you cannot learn the answers. Press the number you see, or I can't see a number. Number keys work too.

Reading your result

Your score is the number of plates you read, out of 15. It is saved in this browser with your personal best, so you can retake the test on another day or another screen and compare.

The result card also names a tendency:

• Typical color vision – you missed at most one plate of each type.
• Protan tendency – you missed two or more red (L-cone) plates and clearly fewer green ones. Reds look darker and are easy to confuse with greens and browns.
• Deutan tendency – the same pattern for green (M-cone) plates. This is the most common type.
• Red-green tendency – you missed red and green plates about equally, so the test cannot tell protan from deutan.
• Tritan tendency – you missed two or more of the four blue plates. True tritan defects are rare; a blue-light filter causes the same pattern far more often.

The strength is called strong when you read one or none of the five red or green plates, and mild otherwise. These labels describe your answers on this screen. They are not a diagnosis.

How common is color blindness?

Red-green color vision deficiency is common in men. A review of survey data by Jennifer Birch (2012) puts it at around 8% of men and well under 1% of women in populations of European descent, with lower rates in many other populations. Sharpe and colleagues (1999) break the male figure down roughly: deuteranomaly (shifted M cones) affects about 5% of men, while protanomaly, protanopia and deuteranopia each affect about 1%.

The genes for the L and M cone pigments sit on the X chromosome. That is why red-green deficiency runs in families through the mother's side: a woman with one affected X usually sees colors normally but has a 50% chance of passing it to each son. Men have only one X chromosome, so a single affected copy is enough. Tritan defects work differently. The S-cone gene is on chromosome 7, the inherited form is very rare, and blue-yellow changes more often come later in life, from eye disease or the natural yellowing of the eye's lens.

Color blindness in everyday life

Most people with a mild deficiency find out by chance: a quarrel about whether a sweater is brown or green, trouble reading a red-on-green chart, or a ripe and unripe fruit that look the same. Common sticking points are traffic lights (people learn the position, not the color), cooking meat, map and chart colors, LED charging lights and colored wiring. Some jobs, such as pilot, train driver or electrician, have color vision standards in many countries, so a professional test is worth doing before you choose such a career.

Phones and computers can help. Most systems have color filters for color blindness in their accessibility settings, and many apps let you point the camera at something and read out its color.

Before you trust the result

The test is only as good as the screen it runs on:

1. Turn off night mode, Night Shift, True Tone, blue-light filters and reading modes. They remove blue and shift reds and greens.
2. Turn the brightness up and look at the screen straight on.
3. Turn off color filters and inverted colors unless you want to test with them.
4. Avoid colored room light and strong glare.
5. Repeat on a second device. A pattern that shows up on two screens is more likely to be about your eyes.

When to see an eye doctor

Plate tests in clinics, such as the charts Shinobu Ishihara first published in 1917, are printed with controlled inks and viewed under standard light. An optometrist or ophthalmologist can confirm the type with such plates, arrangement tests or an anomaloscope. A standard eye test of sharpness, online or in a clinic, does not check color vision. Book an exam if this test shows a tendency on more than one screen, if you need a certified result for work, or straight away if your color vision changes, especially in one eye only, because acquired color vision loss can be an early sign of eye or nerve disease.

You will find more checks like this among our vision tests.

Sources

• Viénot, F., Brettel, H., & Mollon, J. D. (1999). Digital video colourmaps for checking the legibility of displays by dichromats. Color Research & Application, 24(4), 243–252.
• Birch, J. (2012). Worldwide prevalence of red-green color deficiency. Journal of the Optical Society of America A, 29(3), 313–320.
• Sharpe, L. T., Stockman, A., Jägle, H., & Nathans, J. (1999). Opsin genes, cone photopigments, color vision, and color blindness. In K. R. Gegenfurtner & L. T. Sharpe (Eds.), Color vision: From genes to perception (pp. 3–51). Cambridge University Press.
• Ishihara, S. (1917). Tests for colour-blindness. Handaya.

Frequently asked questions