Colour Blindness Simulator

Converts your colours to show how they appear to someone with protanopia, deuteranopia, tritanopia or full colour blindness. It makes immediately obvious why a screen that distinguishes states using only red and green is a problem.

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First colour

Second colour

As seen with normal colour vision

ProtanopiaReds appear darker, making red and green look similarDistinguishable

DeuteranopiaThe most common type — red and green look almost identicalDistinguishable

TritanopiaA rare type, where blue and green are hard to separateHard to tell apart

AchromatopsiaNo colour at all, only lightness remainsHard to tell apart

Never signal with colour alone

Roughly one man in twenty has some colour vision deficiency. A screen that marks success in green and failure in red looks like the same colour to a good number of them. Pair the colour with an icon (✓ ✕) or a word and the meaning survives without it.

The simulation is an approximation, so it is not exactly what someone actually sees. Use it to judge whether a combination is risky, not as a precise rendering.

What this tool does

Four types of colour vision deficiency
Side-by-side check of whether two colours separate
Simulate a whole palette
Contrast shown alongside

Other colour tools

Colour Contrast CheckerCheck text legibility against WCAG Colour Palette GeneratorPull colours that work with a base colour, by rule Colour Shades GeneratorTurn one colour into a 50–900 scale Colour MixerFind the colour between two colours

Colours may look slightly different depending on your screen and its colour profile.