How to use
- Set normal screen brightness and turn off night mode or blue-light filters.
- Click Start the test.
- Type the number you see in each circle and press Next, or choose I can’t see a number.
- Read your result after the last plate.
Options explained
- Red (protan) plates
- The number differs from the background only for the long-wavelength (red) cones; people with protanopia or strong protanomaly have trouble reading them.
- Green (deutan) plates
- The difference is only for the medium-wavelength (green) cones — the most common type of colour blindness.
- Blue-yellow (tritan) plates
- The difference is only for the short-wavelength (blue) cones; tritan deficiency is rare.
Types of colour vision deficiency
| Type | Cones affected | Colours that get confused | How common |
|---|---|---|---|
| Deuteranomaly / deuteranopia | Green (medium-wavelength) | Red, green, brown and orange | The most common — about 6 in 100 men |
| Protanomaly / protanopia | Red (long-wavelength) | Red, green and brown; reds also look darker | About 2 in 100 men |
| Tritanomaly / tritanopia | Blue (short-wavelength) | Blue with green, and yellow with pink | Rare — well under 1 in 1,000 people |
Red-green colour blindness is inherited on the X chromosome, so it affects about 8% of men but only around 0.5% of women of Northern European descent. The “-anomaly” forms are milder: colours are shifted rather than missing.
Getting a reliable result
Use a good screen. A phone or laptop at normal brightness, with night mode, True Tone, blue-light filters and colour filters switched off.
Look straight on. Viewing a laptop screen from an angle changes its colours. Hold a phone at arm’s length.
Answer at first sight. Don’t zoom in or study each plate for long — the plates are designed to be read at a glance.
Confirm with a professional. An optometrist can use printed Ishihara plates, an anomaloscope or the Farnsworth D-15 test for a proper diagnosis, which matters for jobs such as pilot, electrician or train driver.
Frequently asked questions
Is this the Ishihara test?
No. The original Ishihara plates are copyrighted and printed with specially matched inks. These plates follow the same idea but are generated with colour-science formulas for screens.
How accurate is it?
It is a screening only. Screens differ in colour and brightness, so a result here is a hint to get a proper test from an eye doctor or optometrist, not a diagnosis.
Why does the first plate not count?
It is a demonstration plate that everyone should read. If you miss it, the screen settings or the test conditions are probably the problem.
Privacy
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