How to Use This Calculator
- 1
Enter Red Value
Input the red channel value of your source color (0–255).
- 2
Enter Green Value
Input the green channel value of your source color (0–255).
- 3
Enter Blue Value
Input the blue channel value of your source color (0–255).
- 4
Set Severity
Adjust the percentage to control the intensity of the deuteranopia (red-green) color blindness simulation, from 0% (original color) to 100% (full simulation).
- 5
Review Your Results
Observe the simulated hex code, color delta, hue shift, and WCAG contrast ratios for accessibility.
Example Calculation
A web designer wants to see how a specific brand green (RGB 120, 200, 80) appears to someone with 70% deuteranopia (red-green) color blindness.
Red (0–255)
120
Green (0–255)
200
Blue (0–255)
80
Severity (%)
70
Results
#90A964
Tips
Never Rely Solely on Color
When conveying information, always use a secondary indicator in addition to color. For example, use text labels, icons, or patterns alongside color coding in charts to ensure accessibility for color-blind users.
Test with Multiple Protanopia/Deuteranopia Levels
While deuteranopia is the most common, remember that color blindness exists on a spectrum. Test your designs not only for full simulations but also for partial severity levels (e.g., 50-70%) to ensure robustness across a wider range of visual impairments.
Prioritize Contrast Over Hue
For text and important UI elements, focus on achieving sufficient contrast ratios (WCAG AA or AAA) rather than relying on distinct hues. Color-blind individuals may perceive different hues similarly, but they can still differentiate based on lightness and darkness.
Simulating Color Perception for Deuteranopia
The Color Blindness Simulation Calculator provides a vital tool for designers, developers, and content creators to understand how colors appear to individuals with deuteranopia, the most common form of red-green color blindness.
By simulating the perceptual shift for any RGB color, it instantly displays the adjusted hex output, color delta (ΔE), hue shift, and crucial WCAG contrast ratios.
For instance, a vibrant green (RGB 120, 200, 80) at 70% deuteranopia severity might shift to a desaturated yellowish-brown, highlighting potential accessibility issues.
Designing for Colour Accessibility
Designing for color accessibility is not merely an ethical consideration but a practical necessity for inclusive user experiences.
With approximately 8% of males and 0.5% of females worldwide affected by color vision deficiency, relying solely on color to convey information can exclude a significant user base.
This is particularly critical in digital interfaces, data visualizations, and signage where color often signals status, action, or category.
Adhering to guidelines like WCAG (Web Content Accessibility Guidelines) ensures that information remains discernible through other visual cues, such as contrast, texture, or text labels, enhancing usability for everyone.
The Deuteranopia Simulation Matrix
The calculator simulates deuteranopia by applying a specific transformation matrix to the input RGB values.
This matrix mathematically adjusts the red, green, and blue components to reflect how a deuteranope's eye perceives color, where the green-sensitive cones are deficient.
The severity slider controls the blending of the original color with the fully simulated color, allowing for a spectrum of visual impairment.
The output sr, sg, sb represent the simulated red, green, and blue values.
sr = Red × (1 - s) + s × (Red × 0.567 + Green × 0.433 + Blue × 0)
sg = Green × (1 - s) + s × (Red × 0.558 + Green × 0.442 + Blue × 0)
sb = Blue × (1 - s) + s × (Red × 0 + Green × 0.242 + Blue × 0.758)
Here, s is the severity (0-1, 0% = 0, 100% = 1), and Red, Green, Blue are the original channel values (0-255).
Simulating a Brand Green for Deuteranopia
Let's simulate a brand green with RGB values Red = 120, Green = 200, Blue = 80 at a Severity of 70% (s = 0.7).
- Calculate Simulated Red (sr):
sr = 120 * (1 - 0.7) + 0.7 * (120 * 0.567 + 200 * 0.433 + 80 * 0)sr = 36 + 0.7 * (68.04 + 86.6) = 36 + 0.7 * 154.64 = 36 + 108.248 = 144.248->144
- Calculate Simulated Green (sg):
sg = 200 * (1 - 0.7) + 0.7 * (120 * 0.558 + 200 * 0.442 + 80 * 0)sg = 60 + 0.7 * (66.96 + 88.4) = 60 + 0.7 * 155.36 = 60 + 108.752 = 168.752->169
- Calculate Simulated Blue (sb):
sb = 80 * (1 - 0.7) + 0.7 * (120 * 0 + 200 * 0.242 + 80 * 0.758)sb = 24 + 0.7 * (48.4 + 60.64) = 24 + 0.7 * 109.04 = 24 + 76.328 = 100.328->100
The simulated RGB color is (144, 169, 100), which translates to the hex code #90A964.
This shows a clear shift from the original vibrant green to a more muted, yellowish tone.
WCAG Guidelines for Color Perception
The Web Content Accessibility Guidelines (WCAG), developed by the World Wide Web Consortium (W3C), include specific criteria to ensure that digital content is perceivable by individuals with color blindness and other visual impairments.
WCAG 2.1 Success Criterion 1.4.1, "Use of Color," mandates that color must not be used as the only visual means of conveying information, indicating an action, prompting a response, or distinguishing a visual element.
Additionally, Success Criterion 1.4.3, "Contrast (Minimum)," requires a contrast ratio of at least 4.5:1 for normal text and 3:1 for large text against its background.
These guidelines, continuously updated (WCAG 2.2 was released in 2023), are crucial for legal compliance and creating truly inclusive digital experiences in 2025.
Frequently Asked Questions
What is deuteranopia color blindness?
Deuteranopia is a common form of red-green color blindness where the medium-wavelength sensitive cone cells (green cones) in the eye are either absent or non-functional. This results in difficulty distinguishing between shades of red, green, and yellow, which often appear as muted browns or yellows. It is an inherited condition, primarily affecting males, and represents about 1% of the male population globally.
How does a color blindness simulator work?
A color blindness simulator works by applying a mathematical transformation matrix to the RGB values of a source color, mimicking how light is perceived by an individual with a specific type of color vision deficiency. For deuteranopia, this involves shifting red and green components to simulate the reduced sensitivity of green cones, effectively showing how the color would appear to someone with that condition. This helps designers test accessibility.
Why is designing for color blindness important?
Designing for color blindness is crucial for ensuring accessibility and usability for a significant portion of the population. Approximately 1 in 12 men and 1 in 200 women worldwide have some form of color vision deficiency. Failing to consider this can lead to users missing critical information, struggling with navigation, or being unable to interact effectively with digital interfaces, which violates accessibility standards like WCAG.
What are WCAG contrast ratios and why are they relevant?
WCAG (Web Content Accessibility Guidelines) contrast ratios measure the difference in luminance between foreground and background colors to ensure readability for people with various visual impairments, including color blindness. A minimum ratio of 4.5:1 (AA level) is recommended for normal text, and 3:1 for large text, while 7:1 (AAA level) provides enhanced contrast. These ratios ensure that even if colors are perceived differently, the text remains legible.