Color Blindness Simulator: Test Your Designs for Accessibility

Roughly 8% of men and 0.5% of women have some form of color vision deficiency. If your design relies on color alone to convey meaning, a significant portion of your audience may miss critical information. A color blindness simulator shows you exactly what your colors look like through different types of color vision.

Types of Color Vision Deficiency

Color blindness is not a single condition. There are several distinct types, each affecting color perception differently.

People with protanopia cannot perceive red light. Reds appear dark and muted, often looking like dark brown or black. Red-green distinctions are lost entirely. This affects approximately 1% of men.

Colors most affected: Red, orange, and yellow-green shift toward brown and olive tones. Traffic light reds appear very dark.

The most common form of color blindness, affecting about 6% of men. People with deuteranopia cannot perceive green light. Greens and reds both shift toward brownish-yellow tones, making them hard to distinguish from each other.

Colors most affected: Green and red become nearly identical. Green traffic lights appear pale or whitish. Lush green landscapes look brownish-yellow.

A rare condition affecting the blue-yellow spectrum rather than red-green. Blues appear greenish, and yellows appear pinkish or light gray. This affects less than 0.01% of the population.

Colors most affected: Blue shifts toward green-cyan. Yellow and orange shift toward pink. The blue-yellow distinction is lost, but red-green perception remains intact.

Achromatopsia (Total Color Blindness)

Complete absence of color perception. Everything is seen in shades of gray, similar to a black-and-white photograph. This is extremely rare, affecting about 1 in 30,000 people. People with achromatopsia are also typically sensitive to bright light.

Colors most affected: All colors are reduced to luminance values. Dark red and dark green look identically dark. Light blue and light yellow look identically light.

Why Color Accessibility Matters

Legal and Compliance Requirements

WCAG 2.1 (Web Content Accessibility Guidelines) includes specific criteria for color usage:

Guideline 1.4.1 (Use of Color): Color must not be the only visual means of conveying information, indicating an action, or distinguishing a visual element
Guideline 1.4.3 (Contrast): Text must have a contrast ratio of at least 4.5:1 against its background
Guideline 1.4.11 (Non-text Contrast): UI components and graphical elements need at least 3:1 contrast

Many countries have laws requiring web accessibility. In the US, the ADA has been interpreted to cover websites. In the EU, the European Accessibility Act applies to digital services.

Real-World Impact

When color is the only differentiator, colorblind users may struggle with:

Form validation: Red error borders without text or icons
Charts and graphs: Data series distinguished only by color
Status indicators: Green for success, red for error, yellow for warning
Navigation: Active states shown only through color changes
Links: Text links that are only distinguished from body text by color

How to Use Our Color Blindness Simulator

Enter a color using the color picker, hex code, or RGB values
View simulations for all major types of color vision deficiency simultaneously
Compare how your color appears under protanopia, deuteranopia, tritanopia, and achromatopsia
Test color pairs to check whether your foreground and background combinations remain distinguishable

Tips

Test all your brand colors, not just one or two
Pay special attention to colors you use for success/error/warning states
Check that chart and graph colors remain distinguishable under deuteranopia, since it is the most common type
Verify that your link color is distinguishable from body text under all conditions

Designing for Color Accessibility

Never Rely on Color Alone

The simplest rule for color-accessible design: always pair color with another visual indicator.

Instead of	Use
Red border on invalid fields	Red border + error icon + error text
Green/red status dots	Colored dots + labels (“Active”, “Inactive”)
Color-coded chart lines	Color + different line patterns (dashed, dotted)
Colored link text	Color + underline

Choose Distinguishable Palettes

Some color combinations work well for most types of color blindness:

Blue and orange: Remain distinguishable for red-green color blindness
Blue and red: Maintain contrast for most deficiencies
Dark and light variations: Luminance differences survive all types of color blindness

Avoid relying on the distinction between:

Red and green (lost in protanopia and deuteranopia)
Blue and yellow (lost in tritanopia)
Colors with similar luminance (lost in achromatopsia)

Use Patterns and Textures

In charts, diagrams, and data visualizations, supplement color with:

Different line styles (solid, dashed, dotted)
Different shapes for data points (circles, squares, triangles)
Hatching or fill patterns in bar charts
Direct labels instead of color-coded legends

Test Early and Often

Run your color palette through a simulator before finalizing your design, not after. Changing a color scheme late in the design process is expensive. Testing early means you can choose accessible colors from the start.

Frequently Asked Questions

How common is color blindness? About 8% of men and 0.5% of women have some form of color vision deficiency. Deuteranopia (green-blind) is the most common, followed by protanopia (red-blind). Tritanopia and achromatopsia are rare.

Can colorblind people see any colors? Most colorblind people see colors, just differently. Protanopia and deuteranopia affect the red-green spectrum but leave blue perception intact. Only achromatopsia (total color blindness) removes all color perception, and it is extremely rare.

Is the simulation perfectly accurate? Color blindness simulations are mathematical approximations of how colors are perceived. They are very useful for identifying problem areas in your design but cannot perfectly replicate individual experience, since color vision varies on a spectrum even within each type.

What colors are safest for accessibility? Blue is the safest single accent color because it is perceived by nearly all forms of color vision. Combine it with high-luminance contrast (dark on light, light on dark) and non-color indicators for the most robust accessibility.

Do I need to avoid red and green entirely? No. Red and green are fine to use as long as they are not the only way to convey meaning. A red error message with an icon and descriptive text is accessible. A field that only turns red with no other indication is not.

Try our free Color Blindness Simulator to test your designs for color accessibility instantly.