Color Blindness Simulator Simulate how colors appear to people with different types of color vision deficiency.

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Color Blindness Simulator

Simulate how colors appear to people with different types of color vision deficiency.

Enter Colors

Input two colors you want to test together.

View Simulations

See how both colors appear under four types of color vision deficiency.

Assess Accessibility

Determine if your color combination is distinguishable for all users.

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What Is Color Blindness Simulator?

A color blindness simulator shows how your color choices appear to people with different types of color vision deficiency (CVD). Approximately 8% of men and 0.5% of women have some form of color blindness. This tool simulates four types: Protanopia (red-cone absence, ~1% of males), Deuteranopia (green-cone absence, ~1% of males), Tritanopia (blue-cone absence, ~0.01%), and Achromatopsia (complete color blindness, ~0.003%). For each type, the simulator transforms your input colors to show how they would appear to someone with that condition. This is essential for making sure your designs are inclusive and that color is never the only means of conveying information. By testing with this simulator early in the design process, you can identify and fix accessibility issues before they reach users.

Why Use Color Blindness Simulator?

Simulates four major types of color vision deficiency
Side-by-side comparison of two colors under each condition
Shows prevalence statistics for each type
Helps ensure designs are inclusive for all users
Quick way to test color accessibility before deployment

Common Use Cases

UI Accessibility

Test button colors, status indicators, and interactive elements for color-blind users.

Data Visualization

Verify chart colors are distinguishable across all vision types.

Traffic & Safety

Ensure warning colors and status indicators work for color-blind operators.

Education Materials

Design learning materials that are accessible to students with CVD.

Technical Guide

The simulator applies transformation matrices to RGB values that approximate the color perception of each CVD type. Protanopia simulation replaces the L-cone (long-wavelength, red) response with a combination of M and S cone responses. Deuteranopia replaces the M-cone (medium-wavelength, green) response. Tritanopia replaces the S-cone (short-wavelength, blue) response. Achromatopsia converts to grayscale using the standard luminance formula (0.299R + 0.587G + 0.114B). These are simplified linear transformations that approximate the Brettel-Viénot-Mollon simulation model. More accurate simulations would use full spectral rendering with cone response functions, but the matrix approach provides a computationally efficient approximation suitable for real-time web tools. The key insight for designers: if two colors become indistinguishable under any simulation, they should not be the sole differentiator for important information.

Tips & Best Practices

1
Never use color as the ONLY way to convey information — add text labels, icons, or patterns
2
Red-green color blindness is the most common — test reds vs. greens carefully
3
Blue-yellow combinations are generally safe for most color vision types
4
If colors merge under simulation, add contrast (different lightness) or non-color cues
5
Test your most critical color combinations (error/success, enabled/disabled, links/text)

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Frequently Asked Questions

Q How common is color blindness?

About 8% of men and 0.5% of women have some form of color vision deficiency. Red-green deficiency (protanopia and deuteranopia) is the most common, affecting ~6% of males.

Q Is this simulation accurate?

It provides an approximation using linear transformation matrices. The actual experience varies between individuals with the same condition. It gives a useful general indication, not a medically precise simulation.

Q What colors are safe for color-blind users?

Blue and orange/yellow combinations are generally distinguishable across most CVD types. Using different lightness levels (light vs. dark) also helps maintain distinction.

Q Can I use red and green for color-blind users?

You can use red and green, but never as the sole differentiator. Pair color with icons (✓/✕), text labels, or different shading to ensure information is accessible.

About This Tool

Color Blindness Simulator is a free online tool by FreeToolkit.ai. All processing happens directly in your browser — your data never leaves your device. No registration or installation required.