How to Test If You Are Color Blind: A Complete Guide

Approximately 1 in 12 men and 1 in 200 women have some form of color vision deficiency, and many don't know it. Color blindness is far more common than most people realize, and because your brain compensates for the gaps in your color perception, you may have lived your entire life without noticing that the way you see the world is different from everyone else around you.

This guide explains what color blindness really is, the different types, how testing works, and what to do if you suspect your color vision is not quite right.

What Color Blindness Actually Is

The term "color blind" is misleading. Almost no one with a color vision deficiency sees the world in black and white. Instead, color blindness means your eyes have difficulty distinguishing between specific pairs of colors. You still see color, but certain hues look identical or very similar to you when they appear clearly different to people with typical color vision.

Color vision works through three types of cone cells in your retina, each sensitive to a different range of wavelengths: red, green, and blue. When one type of cone is absent or does not function correctly, your brain receives incomplete color information. The result is not a loss of all color, but a specific pattern of confusion between certain colors.

For example, someone with red-green color blindness might see red and green as the same muddy brownish-yellow. They can still see blue, purple, and many other colors perfectly well.

Types of Color Vision Deficiency

There are three main categories of color blindness, named after the type of cone cell that is affected:

Protanopia (Red Deficiency)

Protanopia occurs when the red cone cells are absent or nonfunctional. People with this condition have difficulty distinguishing red from green and may also confuse reds with dark colors like brown and black. Red traffic lights can appear dim or nearly invisible. This affects roughly 1% of men.

Deuteranopia (Green Deficiency)

Deuteranopia is the most common form of color blindness, caused by absent or defective green cone cells. Like protanopia, it makes red and green difficult to tell apart, but the specific shades that cause confusion differ slightly. Greens may appear more beige or tan. About 5% of men have some degree of deuteranopia or its milder form, deuteranomaly.

Tritanopia (Blue Deficiency)

Tritanopia is the rarest form, affecting the blue cone cells. People with tritanopia have trouble distinguishing blue from green and yellow from violet. Unlike red-green deficiency, tritanopia affects men and women equally because it is not linked to the X chromosome. It affects fewer than 1 in 10,000 people.

Most people with color blindness have a milder form called anomalous trichromacy, where the affected cone cells work but respond to a slightly different wavelength range than normal. This causes colors to look "off" rather than completely indistinguishable.

How Ishihara Plates Work

The most widely recognized color blindness test uses Ishihara plates, developed by Dr. Shinobu Ishihara in 1917. Each plate contains a circle filled with dots of varying sizes and colors. Within the dots, a number or pattern is formed using colors that are easy to see with normal vision but difficult or impossible to detect for someone with a color deficiency.

The genius of the Ishihara system is that it controls for brightness. You cannot "cheat" by looking at how light or dark the dots are because the dots within the number and the surrounding dots have similar brightness levels. The only difference is in the color itself. If your cones cannot distinguish those particular colors, the number blends into the background and disappears.

A standard Ishihara test uses 24 or 38 plates. Different plates are designed to detect different types of color blindness. Some plates contain numbers that are visible only to people with color vision deficiency, serving as a control to confirm the person is genuinely trying to identify the patterns.

Signs You Might Be Color Blind

Because color blindness is usually present from birth, many people assume that everyone sees colors the same way they do. Here are common signs that suggest you should take a test:

• You have difficulty telling whether meat is cooked (distinguishing red from brown)
• Friends or family have pointed out that your clothing combinations clash in ways you cannot see
• You struggle with color-coded charts, maps, or graphs at work or school
• You have trouble telling the difference between green and orange or red LEDs on electronic devices
• You find it hard to identify ripe fruit, particularly telling red apples from green ones
• You confuse colors when labeling or sorting objects
• You had difficulty with crayon or paint colors as a child, often mislabeling greens, reds, or browns

Having one or two of these experiences occasionally is normal. Having several of them consistently is worth investigating.

How Online Color Blind Tests Work

Online color vision tests simulate the Ishihara method by displaying colored dot patterns on your screen and asking you to identify numbers or shapes within them. You can take a free color blind test right now that walks you through a series of plates and gives you an immediate assessment of your color vision.

Online tests are a useful screening tool, but it is important to understand their limitations. Your monitor's color calibration, brightness settings, ambient lighting, and screen quality all affect the accuracy of the results. A test that looks perfectly calibrated on one screen may display slightly shifted colors on another, potentially leading to false positives or false negatives.

For this reason, online tests are best used as a first step. They can give you a strong indication of whether you should pursue further testing, but they should not be considered a definitive diagnosis.

Clinical Testing: The Gold Standard

If an online test suggests you may have a color vision deficiency, or if you need a certified result for professional reasons (certain careers in aviation, transportation, and the military require documented color vision testing), schedule an appointment with an optometrist or ophthalmologist.

Clinical testing uses physical Ishihara plates under standardized lighting conditions, eliminating the screen calibration issues that affect online tests. Your eye doctor may also use the Farnsworth-Munsell 100 Hue Test, which asks you to arrange colored caps in order. This test is particularly useful for measuring the severity of your deficiency and identifying exactly which colors are most problematic for you.

When to See an Eye Doctor

You should see an eye care professional if:

• An online screening test indicates possible color vision deficiency
• You notice a sudden change in your color perception (this can indicate a medical issue unrelated to inherited color blindness)
• Your job requires accurate color discrimination
• A child is struggling with color identification at school

Inherited color blindness cannot be cured or corrected, but knowing about it allows you to develop strategies and use tools that compensate for it. Special filter glasses, like those made by EnChroma, can enhance color distinction for some types of deficiency, though results vary significantly between individuals.