Color Blindness Test

First, what this page is and is not

This page lets you try a simplified version of the idea behind the Ishihara color vision test: five plates of colored dots, each hiding a single digit. It is a curiosity and a reference, not a medical device. Whether someone has a color vision deficiency can only be established by a qualified eye care professional using standardized plates or other validated tests under controlled lighting. Do not use your score here to decide anything about schooling, jobs, driving or any role that has a color vision requirement; if such a requirement applies to you, take the exam that the relevant organization asks for. Everything below is general information and not medical advice.

How the Ishihara test works

The Ishihara test is named after the Japanese ophthalmologist Shinobu Ishihara, who published it around 1917. It is the best-known example of a pseudoisochromatic plate, meaning a plate where the figure and the background are made of colors that look different to most people but are easily confused by people with certain deficiencies. A circle is filled with dots of varying size and brightness. The dots that form a digit or shape use one set of colors, and the surrounding dots use another. A person with typical color vision sees the figure because the two color groups look clearly different. A person with red-green deficiency may see the two groups as nearly the same, so the figure disappears, or they may read a different number from the one a typical viewer reads. The dot sizes and brightness values are deliberately scattered so that the figure cannot be guessed from lightness differences alone.

Professional plate sets are printed with tightly controlled inks. Each plate has a documented reading for typical vision, for the common red-green deficiencies and for people who cannot read it, and sets usually begin with a demonstration plate that everyone can read to confirm they understand the task. This page has none of that structure or validation.

Types of color vision deficiency

The retina contains three kinds of cone cells that respond to long (L), medium (M) and short (S) wavelengths. Which cone type is weak or missing determines the type of deficiency.

When a cone type works but with shifted sensitivity the condition is usually called anomalous trichromacy (color weakness); when the cone type is absent it is dichromacy (color blindness). Complete absence of color vision is very rare. The common red-green forms are linked to genes on the X chromosome, which is why they are far more common in men than in women. Published reviews commonly report figures up to roughly 8% for men of Northern European ancestry and under 1% for women, with lower figures reported in some other populations. The numbers depend on the population and the method used, so treat them as rough orientation only. Blue-yellow deficiencies are much rarer. Color perception can also change later in life because of eye disease, optic nerve problems, certain medicines or the natural aging of the lens, so a sudden change in how you see colors is a reason to see an eye doctor.

How this screen test differs from a clinical test

• Display and environment: every monitor renders color differently, and brightness, color temperature, night mode, blue-light filters and room lighting all alter what you see. A clinical test uses printed plates under specified light.
• Plate design: the plates here are generated at random from an orange-brown background palette and a green figure palette. Their colors have not been validated the way professional plates have.
• No typing of the deficiency: an examiner uses specific plates to estimate the type and degree of a deficiency. This page only presents five red-green confusion plates and is nearly blind to blue-yellow problems.
• Guessing is possible: you enter a digit from 1 to 9, so a lucky guess can be right (see the table below).
• Other test formats exist: eye clinics may also use arrangement tests, in which you sort color caps in order of hue, and other validated methods.

Reference table 1: brightness of the dot colors

The figure dots (green) and background dots (orange) are chosen to have similar brightness so that you cannot read the digit from lightness alone. The table lists the relative luminance of each color, computed at build time with the WCAG formula (0 is black, 1 is white). The mean luminance is 0.391 for the background group and 0.355 for the figure group, so the groups are close but individual colors overlap in range.

Equal luminance on paper does not guarantee equal brightness on every screen, and overlapping dots or anti-aliased edges can leave faint lightness clues. That is one more reason to treat the result as a rough impression.

Reference table 2: how likely is a lucky guess?

Each plate hides one digit from 1 to 9, so a blind guess has a 1/9 chance of being right. The table shows the chance of getting at least a given number of the five plates right by guessing every one (a binomial calculation). Pressing skip counts as a miss.

One or two correct answers can easily come from luck, so do not read much into a difference of a single plate. If a digit is truly invisible to you, press skip rather than guess; invented answers make the score meaningless.

Setting up a fair attempt

1. Turn off night mode, blue-light filters, color filters and dark-mode browser extensions.
2. Set the screen brightness to medium or higher and look straight at it. Avoid glare from windows or lamps.
3. Wear glasses or contact lenses as you normally do.
4. Type the first digit you perceive instead of staring and guessing. If nothing shows, skip.
5. If possible, try again on a second device. A big difference between devices means the screen is influencing the outcome.

Reading the result

If you read all five plates, it means none of them was hard to read on this particular screen. It does not mean your color vision is normal. If you missed some plates, it can be a hint worth following up, but screen settings, concentration and typing slips all contribute. What matters more is real life: trouble with traffic signals, map legends, judging whether meat is cooked, matching clothes, or telling colored pencils or wires apart. If such problems come up often, a proper test at an eye clinic is far more informative than this page, whatever your score. If you design documents or interfaces, a useful habit is never to carry meaning by color alone. Add labels, icons, patterns or shapes, and check text colors with the contrast checker and your palettes from the color palette generator.

Frequently Asked Questions

Related tools

• Color contrast checker - check text and background contrast
• Color palette generator - build color combinations
• Color-Word Reaction Game - practice ignoring conflicting words and colors