Color Blindness Simulator
Simulates your color scale under deuteranopia, protanopia and tritanopia, then flags the specific shade pairs that stop being distinguishable — the ones you should not rely on alone to carry meaning.
The full 50–950 scale is simulated for each type of color vision.
Normal vision
How the scale is designed to look
Deuteranopia
~1 in 16 men
Green cones are missing. The most common form — reds and greens collapse toward the same yellow-brown.
Every shade stays distinguishable from the others.
Protanopia
~1 in 100 men
Red cones are missing. Similar confusion to deuteranopia, but reds also lose brightness and go darker.
Every shade stays distinguishable from the others.
Tritanopia
~1 in 10,000
Blue cones are missing. Blues and greens converge, and yellows can read as pink.
Every shade stays distinguishable from the others.
Frequently asked
How accurate is the simulation?
It uses the Machado, Oliveira and Fernandes (2009) matrices at full severity, applied in linear sRGB. These are the same matrices most accessibility tooling uses. They preserve the grey axis exactly — white stays white, grey stays grey — which is the first thing to check in any implementation of this.
What does a flagged pair actually mean?
That two shades which are clearly different to you land close enough together under that type of vision to be confused. Only pairs that were distinguishable before and stop being so are reported — shades that already looked alike are your palette's business, not this tool's.
So should I avoid those colors?
Not necessarily. The rule is not to avoid them but to avoid making them the only signal. If two shades collide, add a second cue — an icon, a label, a pattern, a position — so meaning does not rest on color alone.
Why is deuteranopia listed first?
Because it is by far the most common, affecting roughly 1 in 16 men. Protanopia is about 1 in 100 and tritanopia is rare, around 1 in 10,000, and unlike the other two it affects blues rather than reds and greens.
Is this the same as checking contrast?
No, and you need both. Contrast asks whether text is readable against a background; this asks whether two colors can be told apart at all. A pair can pass contrast and still be indistinguishable to someone with color vision deficiency.