UtilibyWritten by the Utiliby editorial team · Last updated October 13, 2026 · Rules and formulas reviewed October 2026
What this free online color blind test and simulator does
This free color blind test shows you 10 colored dot plates, each hiding a number. If you read the numbers, your color vision is probably typical. If some of them vanish, especially the red-green plates, that can be a sign of red-green color vision deficiency, the most common form of color blindness. You get a clear result, a plate-by-plate breakdown and a way to see the same plates as someone with color blindness would.
The second tab is a color blindness simulator. Load any image, or use the built-in sample, and see it as it appears with protanopia, deuteranopia, tritanopia or achromatopsia, with a severity slider and one-click PNG download. It is useful for designers, teachers, developers and anyone who wants to understand what color blindness looks like. Everything runs in your browser, so images and results stay private.
How to take the color blind test
- Prepare your screen. Medium or high brightness, no night mode, no color filters, normal room light, about an arm's length away.
- Start the test. Press Start. Each plate is a circle of dots in different sizes and colors.
- Type the number. Enter the one or two digit number you see and press Enter or Next. If you cannot see any number, press I see no number.
- Read your result. You get the screening result, scores for each type of plate, a plate-by-plate table and the answers.
- Compare views. Use the viewer on the result page to see the plates as they appear with protanopia, deuteranopia, tritanopia or achromatopsia.
- Share or save. Print / save as PDF, copy the summary or download the CSV. You can retake the test at any time.
How color blind test plates work
A pseudoisochromatic plate hides a figure in a field of dots. The figure and the background are made of dots in colors that people with color vision deficiency confuse, but that people with typical color vision tell apart. The dots also vary randomly in size and brightness, so the figure cannot be found by outlines or brightness alone. If you cannot separate the two groups by color, the figure disappears.
In this tool, figure dots and background dots are given the same range of luminance, so brightness gives nothing away. Red-green plates use orange or red-orange dots against yellow-green or green dots. Blue-yellow plates use cyan against green. The difficulty rises as the two colors move closer together. The control plate uses strong brightness contrast, so everyone should read it. The red-green and blue-yellow plates were checked against the same color vision simulation used in the Simulator tab.
| Plate | What it screens | Who may miss it |
|---|---|---|
| Control | Display and viewing conditions | Nobody, if conditions are good |
| Red-green level 1 to 2 | Clear red-green deficiency | Protan and deutan, including many mild cases |
| Red-green level 3 to 4 | Mild red-green deficiency | Mostly anomalous trichromats (mild) |
| Blue-yellow | Blue-yellow (tritan) difficulty | Rare; also screen or age effects |
How to read your color blind test result
| What happened | What it suggests |
|---|---|
| Read everything or miss at most one red-green plate | No sign of deficiency in this screening |
| Missed two or more red-green plates, but only the harder levels | Possible mild red-green deficiency |
| Missed several easy red-green plates | Likely red-green deficiency (protan or deutan) |
| Missed a blue-yellow plate | Possible blue-yellow difficulty, or a screen or lighting effect |
| Missed the control plate | The test is unreliable; fix screen and lighting and retake |
These rules are an educational interpretation, not a clinical scale. They have not been validated against a clinical population. If your result surprises you, retake the test on another screen or in different light, then book an eye exam if it persists.
Types of color blindness
Typical color vision uses three kinds of cone cells that respond to long (red), medium (green) and short (blue) wavelengths. A color vision deficiency happens when one kind of cone is missing, faulty or shifted. The result depends on which cone is affected and by how much.
| Type | Cone affected | Prevalence | Effect |
|---|---|---|---|
| Protanomaly | Red, weak | about 1% of men | Reds dull, red-green confusion |
| Protanopia | Red, missing | about 1% of men | Reds look very dark, strong red-green confusion |
| Deuteranomaly | Green, weak | about 5% of men | The most common type, mild red-green confusion |
| Deuteranopia | Green, missing | about 1% of men | Strong red-green confusion |
| Tritanomaly, Tritanopia | Blue, weak or missing | under 0.01% | Blue-green and yellow-pink confusion |
| Achromatopsia | None working | about 1 in 30,000 | Little or no color, often with light sensitivity |
The Types tab shows a rainbow strip as seen with each type, which is a quick way to understand why a red alert on a green background, or a green and orange chart, can be unreadable for many users.
How the color blindness simulator works
The simulator uses the physiologically based model of Machado, Oliveira and Fernandes (2009), the same family of matrices used in many accessibility tools and browser developer tools. Each pixel is converted from sRGB to linear light, multiplied by a 3 by 3 matrix for the chosen deficiency, blended with the original by the severity slider, and converted back. Achromatopsia is shown as a luminance-only grayscale.
The simulation is a design aid. It shows what is likely to be lost, such as the difference between a red and a green status light, so you can add labels, shapes or lightness differences. It cannot represent the full range of individual experience.
Designing for color blind users
- Never use color alone. Pair color with text, icons, patterns or position (WCAG 1.4.1).
- Use lightness differences. Color blind users see lightness well. Make categories differ in brightness as well as hue.
- Avoid red-green pairs for status, charts and maps. Use blue and orange, or add symbols.
- Choose color-blind-safe palettes such as Okabe-Ito or ColorBrewer's safe schemes for charts.
- Label lines and bars directly instead of relying on a legend.
- Check contrast of text and key graphics with a contrast checker.
- Test with a simulation before you publish.
Living with color vision deficiency
Most people with color vision deficiency manage well. Useful strategies include labeling clothes and paints, using the color filter settings that now ship with Windows, macOS, iOS and Android, choosing apps with a color blind mode, asking for color names in charts, and using a color identifier app. Some jobs, for example in aviation, rail, the armed forces, electrical work and some emergency services, have color vision standards, and a clinical test is needed.
Limits of an online color blind test
Monitors vary widely in color accuracy. Night modes, color management and viewing angle can shift colors. Quick screening tests also have false positives and false negatives. Age-related lens yellowing, some eye diseases and some medicines can change color perception. For any decision that matters, rely on a clinical test.
Privacy
The test and the simulator run in your browser. Images you choose are processed on your device and are not uploaded. Test answers are not stored. Reloading the page clears the results.
Related free tools
Use these free online tools together with this one:
- Check whether text and background colors are readable with the color contrast checker.
- Test a web page for common accessibility problems with the HTML accessibility checker.
- Work through accessibility requirements with the WCAG checklist generator.
- Build a color scheme with the color palette generator.
- Plan lessons that do not rely on color alone with the lesson plan template generator.
- Build an email template that does not rely on color alone with the HTML email template builder.
Frequently asked questions
How does this color blind test work?
You see 10 dot plates, each hiding a one or two digit number. People with typical color vision read the number from the difference in hue. For some people with a color vision deficiency, the hue difference is invisible, so the number disappears. The tool includes a control plate, seven red-green plates of rising difficulty and two blue-yellow plates, then gives a screening result.
Is this the Ishihara test?
No. The Ishihara test is a published set of printed plates. This tool generates its own original dot plates in your browser using the same general principle, so it is not a copy and is not a clinical test. It is a quick online screening.
Is an online color blind test accurate?
It is a useful first check, but screens differ in brightness, color accuracy and settings, and a quick test has limits. A result that suggests a deficiency is worth confirming with an optometrist or ophthalmologist. A normal result does not guarantee normal color vision.
What do the plate levels mean?
Red-green plates start with strong orange against green (level 1) and get harder as the two colors move closer (level 4). Mild deficiencies usually pass the easy plates and fail the hard ones. Missing the easy plates suggests a stronger deficiency.
Why is there a control plate?
The control plate uses strong brightness contrast, so almost everyone can read it. If you miss it, the problem is probably the screen, the lighting or the way you are viewing it, not your color vision.
How do I get the most reliable result?
Use a normal computer monitor or good phone screen at medium or high brightness. Turn off night mode, color filters and blue-light apps. Sit about an arm's length away in even room light. Take the test once without squinting or tilting the screen.
What is the difference between protanopia, deuteranopia and tritanopia?
Protanopia is the absence of working red cones, deuteranopia of green cones and tritanopia of blue cones. The first two cause red-green confusion and are by far the most common. Tritanopia is very rare. The milder forms with weak cones are called protanomaly, deuteranomaly and tritanomaly.
Can this test tell protan from deutan?
No. It screens for red-green and blue-yellow difficulty and rates difficulty by plate level. Telling protan from deutan, and measuring severity precisely, needs clinical tests such as the Farnsworth D-15, the Hardy-Rand-Rittler plates or an anomaloscope.
How common is color blindness?
Roughly 1 in 12 men (about 8%) and 1 in 200 women (about 0.5%) have some form of red-green color vision deficiency. Blue-yellow deficiency and complete color blindness are much rarer.
Can color blindness be cured?
There is currently no cure for inherited color vision deficiency. Special filter glasses and contact lenses may help some people tell certain colors apart, but they do not restore normal color vision. Acquired color vision loss from disease, medicines or injury should be checked by a doctor.
How does the color blindness simulator work?
It converts each pixel to linear light and applies the Machado, Oliveira and Fernandes (2009) matrices for protanopia, deuteranopia and tritanopia, or a luminance conversion for achromatopsia. A severity slider blends between the original and the full simulation.
Is the simulation exactly what a color blind person sees?
No. It is a good approximation of typical appearance. People differ, and mild deficiencies are not the same as full dichromacy, which is why the severity slider is included.
Are my images uploaded?
No. Images are loaded and processed in your browser only. Nothing is sent to a server.
How can designers use the simulator?
Check charts, maps, status colors, graphs and brand palettes. If two categories become the same color in a simulation, add labels, patterns, icons or a different lightness. Do not rely on color alone, as WCAG 1.4.1 requires.
What should I do if my result suggests color blindness?
Book an eye exam to confirm. Many people with color vision deficiency live and work without difficulty, and simple adjustments such as labeled colors, color filters in your operating system and high contrast modes help. Some careers, such as aviation and some electrical or emergency roles, have formal color vision requirements.
Can children take this test?
Children who can read numbers may try it with an adult's help. Because a screening can be wrong, an eye care professional is the right person to test a child if there is a concern about learning or color difficulty.
What can I print or save?
Print / save as PDF, CSV and Copy summary use the tab you are viewing: the test results, the simulation settings with the simulated image, or the table of types. You can also download the simulated image as a PNG.
Sources and further reading
- Machado, Oliveira and Fernandes (2009), A Physiologically-based Model for Simulation of Color Vision Deficiency, IEEE Transactions on Visualization and Computer Graphics, for the simulation matrices.
- National Eye Institute (US), Color Blindness, for causes, types and typical prevalence in men and women.
- W3C WCAG 2.2, Success Criterion 1.4.1 Use of Color, for not using color as the only visual means of conveying information.
- Okabe and Ito, Color Universal Design, for color-blind-safe palettes referenced in the design tips.
Sources were consulted in October 2026. Standards and rules can change, so always check the official page for your situation.