How Common Is Color Blindness?

Prevalence by type

Almost all colour blindness is red-green. Blue-yellow and total colour blindness together make up only a small fraction of cases.

• Deuteranomaly (mild green), the most common, around 5% of men.
• Deuteranopia (strong green), around 1% of men.
• Protanomaly (mild red), around 1% of men.
• Protanopia (strong red), around 1% of men.
• Tritan (blue-yellow), rare, and roughly equal between the sexes.
• Achromatopsia (total), very rare, around 1 in 30,000.

Why men are affected more

Red-green colour blindness is X-linked, and men have only one X chromosome, so a single affected gene causes it. Women have two Xs and usually need both affected, hence the roughly 16-to-1 gap between men and women for red-green types. Blue-yellow deficiency isn't X-linked, so it doesn't show this pattern. See the genetics for the full explanation.

Differences by ethnicity

Prevalence varies between populations. Studies generally find the highest rates of red-green deficiency among men of Northern European descent (around 8%), with somewhat lower rates reported in some Asian, African and Indigenous populations. Figures differ between studies and testing methods, so treat exact percentages as approximate.

Everyday scale

Because 1 in 12 men is affected, most classrooms, teams and workplaces include someone who is colour blind, often without anyone knowing. That's a good argument for not relying on colour alone in charts, maps, signage and interfaces. You can check how a design looks with the colour blindness simulator.

Wondering if you're one of them? Take the free color blind test or read the key facts.