Color Blindness Simulator

Color blindness (color vision deficiency) is the reduced ability to distinguish certain colors. It is usually caused by an absence or malfunction of one or more types of cone photoreceptors in the retina. Most people with color blindness can still see colors — they just cannot distinguish some combinations, especially red and green.

The most common types are protanopia (missing red cones), deuteranopia (missing green cones), and tritanopia (missing blue cones). Anomalous forms — protanomaly, deuteranomaly, and tritanomaly — occur when cones are present but shifted in sensitivity rather than completely absent. Achromatopsia is total color blindness where only brightness is perceived.

Approximately 8% of men and 0.5% of women of Northern European descent have some form of color vision deficiency. Red-green color blindness (protanopia + deuteranopia + their anomalous variants) is by far the most common. Tritanopia and achromatopsia are much rarer, affecting fewer than 1 in 10,000 people.

Avoid using color as the only means of conveying information — pair it with icons, patterns, or labels. Use high-contrast color pairs and test your palette with simulation tools. Prefer color schemes that remain distinguishable under the most common deficiencies (deuteranomaly/deuteranopia). Tools like this simulator let you check whether your chosen colors still communicate their intended meaning when viewed by someone with a color vision deficiency.

WCAG 1.4.1 (Use of Color, Level A) requires that color is not used as the sole visual means of conveying information or indicating an action. WCAG 1.4.3 and 1.4.6 mandate minimum contrast ratios of 4.5:1 (AA) and 7:1 (AAA) between text and its background. Meeting these contrast requirements also improves readability for users with color vision deficiency because high-contrast combinations tend to remain distinguishable across most CVD types.