Free Online Color Blindness Simulator Tool

1. Enter or pick a source hex color.
2. Compare the five preview swatches side-by-side: Normal, Protanopia, Deuteranopia, Tritanopia, Achromatopsia.
3. If two colors that should look different collapse together in any panel, add a non-color cue — icon, label, position or contrast difference.

Color vision deficiency affects roughly 8% of men and 0.5% of women of northern-European descent (Sharpe et al., 1999). Protanopia is the absence of working long-wavelength (red) cones, deuteranopia of medium-wavelength (green) cones, and tritanopia of short-wavelength (blue) cones; achromatopsia is total color blindness producing grayscale perception.

This simulator applies the published Brettel-Viénot-Mollon 3×3 matrices in sRGB space — the same transforms used by tools like Coblis — to approximate each deficiency. Designers use it to verify that a UI doesn't rely on color alone to convey meaning (status badges, chart series, error states); educators use it to demonstrate inclusive design; accessibility specialists pair it with the contrast checker to catch issues before they ship.

Previews update instantly in-browser, so iterating on a swatch is a single keystroke loop.