Why check color blindness simulation?
A significant share of the population has some form of color vision deficiency, such as red-green or blue-yellow color blindness, so what a designer sees on screen isn't always what a user perceives. A UI that uses red and green alone to signal success or failure looks nearly identical to a user with protanopia or deuteranopia, which can cause important information to be missed entirely. Any design that leans on color alone to distinguish meaning deserves a second look for accessibility.
Enter two color codes and this tool applies protanopia, deuteranopia, and tritanopia simulation, then calculates distinguishability using the WCAG contrast ratio formula. If the ratio comes out low, reinforce the color difference with icons, text labels, or patterns rather than relying on hue alone. Since this is an approximate simulation, pair it with a dedicated color blindness testing tool for critical work.
Frequently Asked Questions
It applies an approximate transformation matrix that mimics how certain color receptors respond differently in protanopia, deuteranopia, and tritanopia to reproduce what those users would actually see.
Don't rely on color alone to convey information — increase the brightness difference or add icons, patterns, or text labels alongside color.