Colour Vision Test: Can You Spot the Odd Shade?

This measures colour discrimination — how small a difference in shade your eyes can still separate. The tiles share a hue and saturation, and only the lightness of one of them moves, by less and less each level.

Two things matter more than your eyes here: screen brightness and ambient light. A dimmed phone in a bright room will cost you several levels, so if you want an honest score, turn the brightness up and get out of direct sunlight.