What contrast ratio is required for WCAG AA compliance?

WCAG 2.1 Level AA requires a contrast ratio of at least 4.5:1 for normal body text and at least 3:1 for large text (18pt or 14pt bold) and user interface components (buttons, input borders).

What is the difference between Protanopia and Deuteranopia?

Protanopia is red-blindness caused by the absence of red photoreceptors (L-cones). Deuteranopia is green-blindness caused by the absence of green photoreceptors (M-cones), representing the most common form of red-green color blindness.

WCAG Color Contrast Checker & Simulator

Verify compliance with W3C Web Content Accessibility Guidelines (WCAG 2.1) Level AA & AAA. Real-time contrast ratios and color blindness matrix simulation for protanopia, deuteranopia, and tritanopia. 100% private in-browser.

High-Impact Accessible Typography

Good contrast is essential for readability and accessible user interface design. Over 300 million people worldwide have color vision deficiency. Meeting WCAG AAA standards ensures your web applications are easily readable in direct sunlight, low-contrast laptop displays, and for all users.

Interactive Action Button

👁 Color Vision Deficiency Simulation

Normal Vision

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Protanopia (Red-Blind)

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Deuteranopia (Green-Blind)

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Tritanopia (Blue-Blind)

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Achromatopsia (Monochrome)

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Accessibility Engineering Standards

W3C Relative Luminance

Uses the CIE 1931 standard color space formula with non-linear sRGB gamma correction to compute mathematically precise perceptual brightness.

Brettel-Machado Matrix

Simulates real-world cone receptor response in human eyes by projecting RGB vectors into physiologically measured LMS color space.

Zero Tracking

Color choices and brand palette testing happen entirely on the client, keeping unreleased product designs completely confidential.