Measure, don’t just pass or fail
A fixed plate set can only say “read it” or “didn’t”. An adaptive staircase per cone finds how much color contrast you actually need, which is what separates a mild anomaly from dichromacy.
About Us
About colorblindtest.app
We build a free, adaptive color blind test that measures each of your three cone types — and keeps your results on your own device.
Our approach
One cone at a time.
Every plate is tuned so only one cone type can see the digit. Read it and the next one gets subtler.
- Plates per test
- 19
- Cones scored
- 3
- Minutes
- ~2
Plates per test
Cones scored
Minutes
What we make
A color blind test that measures, in your browser
Most free online colorblind tests show a fixed set of scanned Ishihara plates. Those plates were designed for printed paper under daylight, so on a screen they are only loosely calibrated, and they only screen for red-green deficiency. A pass/fail answer also says little about how strong a deficiency is.
colorblindtest.app keeps the familiar format — a circle of dots hiding a digit — but computes the colors. Using a standard model of human cone responses, each plate’s digit and background differ for only one cone type. Random brightness noise on every dot removes luminance cues. An adaptive staircase then raises or lowers the color contrast on each axis to find your threshold, which becomes a 0–100 score for your red, green, and blue cones.
The entire test runs in your browser. Nothing is downloaded, there is no account, and your results are stored only in local storage. The method is documented in full on how it works and in the FAQ.
Origins
Two centuries of color vision testing
1794 — Dalton describes it
The chemist John Dalton gave the first scientific account of color blindness in 1794, describing his own and his brother’s confusion of pink and blue. For decades “daltonism” was the common name for it. DNA extracted from his preserved eye in the 1990s showed he was a deuteranope.
1875 — testing becomes a safety issue
After the Lagerlunda rail collision in Sweden, Frithiof Holmgren argued that color-blind signalmen were a hazard and introduced a wool-sorting test for railway staff. Color vision screening for transport jobs has been standard ever since.
1917 — Ishihara’s plates
Shinobu Ishihara, an ophthalmologist in the Japanese army, published plates of colored dots hiding numbers. They were cheap, fast, and remarkably sensitive to red-green deficiency, and they remain the most widely used color vision screening test in the world.
Today — cone-isolating tests
Research tests such as the Cambridge Colour Test, and consumer tests like EnChroma’s, compute colors on a screen that differ for only one cone type and measure a threshold for each. That makes it possible to score red, green, and blue sensitivity separately — including the blue-yellow deficiencies Ishihara plates miss.
Design principles
What we optimize for
Never the same plate twice
Plates are generated on the fly from a random seed — dot packing, digit, base color, and brightness noise — so the test can’t be memorized and every retake counts.
Fast on any screen
The plate and keypad fit on one phone screen. No page reloads between plates, no video, no app to install. A full run takes about two minutes.
Honest about limits
Consumer screens aren’t calibrated, so we show scores as a screening result, explain the uncertainty, and point you to an eye-care professional when a score is low.
Contact
Get in touch
A result that looks wrong on your device, a bug, a research question, or accessibility feedback — we read every message.
Email usMore about the test and the site: