Free Online Color Blindness Test Tool

1. Sit a comfortable distance from your screen with normal brightness.
2. For each plate, type the number you see and click Next.
3. After the final plate, review your per-category score.
4. Click Restart to take the test again — or book an optometrist if you'd like a clinical check.

Ishihara plates, invented in 1917 by Shinobu Ishihara, are still the standard quick screen for red-green colour vision deficiency. A number is drawn in one colour palette against a background in a confusable palette: someone with normal vision sees the digit easily, while someone with protan or deutan deficiency sees a different number or nothing at all.

Designers check whether their colour choices will survive common deficiencies (which affect roughly 8% of men and 0.5% of women of Northern European descent). Curious users get a rough sense of where they fall. Parents screen children before a school sight test. This tool uses five CSS-rendered plates — one control, three red-green and one blue-yellow — to give a basic indication.

It is not a clinical test. Screen brightness, ambient light and monitor calibration all affect what you see, and a real diagnosis requires a calibrated test conducted by an optometrist or ophthalmologist. Treat results as screening only, not medical advice.