A free Ishihara-style color blind test. What number can you read?
Ready when you are
This is a free online color blind test built in the style of the classic Ishihara plates that clinics use to screen for colour vision deficiency. Each plate is a disc of coloured dots, and hidden among them is a single digit drawn in a different hue from the dots around it. You read the number, tap it, and move on to the next plate.
The trick is that the dots vary in lightness at random, so you cannot cheat by hunting for a lighter or darker patch. Hue is the only thing that separates the figure from its background. That is what makes the plate a test of colour perception specifically, rather than a test of contrast or shape recognition.
Every plate starts by picking a random digit from 0 to 9 and a base hue for the background dots. The figure dots take a second hue offset from the first. Both sets share the same range of lightness and saturation, and the dots are scattered so no edge or outline gives the digit away. A fixed seed drives the layout, which is why the plate you see on the play screen matches the one shown again on the reveal — same dots, same positions, so you can look back and check what you missed.
Difficulty comes down to one number: the hue gap between the figure and the background. Plate one uses a wide gap, so the digit almost pops off the disc. Each plate after that shrinks the gap, and by the fifth plate the two hues are close neighbours on the colour wheel. Someone with typical colour vision can usually still read the last plate, but it takes a moment. If your vision leans toward red-green deficiency, the later plates are where the number tends to dissolve.
Do not stare at the centre and wait. Let your eyes drift across the whole disc so your peripheral vision can catch the shape, then look back. Softening your focus, as if looking through the plate, often makes a faint digit resolve when a hard stare does not. Good, neutral lighting helps too: a warm bulb or a screen with a heavy colour cast shifts every hue and can flip a plate from readable to impossible. If you are stuck between two digits, trust the first shape your eye settled on rather than talking yourself out of it.
Each plate is judged as a straight yes-or-no. Read the digit correctly and you bank the full ten points for that plate; miss it or skip it and you get nothing — there is no partial credit and no perceptual distance calculation, because a number is either right or it is not. Across the five plates that puts the ceiling at fifty points. Since the gap narrows every round, a run of low scores at the start means nothing, while dropping the last plate or two is the usual pattern and still leaves you with a solid total.
Treat this as a game, not a diagnosis. It is a fun way to see how your eyes handle shrinking hue differences, and it can hint at a red-green weakness — but a real assessment of colour vision deficiency uses standardised, calibrated plates under controlled lighting and is read by an eye-care professional. Screen colours, brightness settings, and ambient light all change what you see here. If you keep failing the easy plates, take it as a nudge to book a proper test, not as a result in itself.
Curious about the science behind colour vision? Read our piece on how many colours the human eye can see and the one on tetrachromacy and expanded colour vision. If you would rather train your eye than test it, the guide to sharpening your colour perception is a good place to start, or jump into the other colour games on the site.
