WCAG 2.1 & APCA Color Contrast Checker
Verify accessibility compliance for web interfaces, game HUDs, and digital typography with instant smart luminance correction.
Direct Answer & Pipeline Overview
WCAG Color Contrast Checker is a specialized, 100% client-side engineering utility developed by Atlyxen Studios. It processes calculations and conversions directly inside your browser memory using hardware-accelerated WebAssembly and WebGL, guaranteeing instant results with zero server file transfers and zero data retention.
How to Use the WCAG Color Contrast Checker
Pick Foreground Color
Choose your text or icon color using the native color picker or type an exact hex code.
Pick Background Color
Select your surface or container background color.
Review Compliance Matrix
Verify whether the pair passes WCAG AA (4.5:1) or AAA (7.0:1) thresholds for normal text, large text, and UI components.
Use Smart Auto-Fixer
If the pair fails, click Adjust to AA or Adjust to AAA to automatically calculate the nearest accessible hue.
Key Technical Capabilities
Instant relative luminance calculation according to W3C WCAG 2.1 and 2.2 specifications
Evaluates Normal Text (4.5:1 AA, 7.0:1 AAA), Large Text (3.0:1 AA, 4.5:1 AAA), and UI Components
APCA (Advanced Perceptual Contrast Algorithm) lightness contrast score estimation
Smart Auto-Fixer providing one-click adjustments to achieve guaranteed AA or AAA compliance
Color blindness vision simulation for Protanopia, Deuteranopia, Tritanopia, and Achromatopsia
Real-world interactive component sandbox previewing headings, body copy, and action buttons
Pre-curated accessible color palettes for dark and light modern design systems
One-click CSS code export with inline compliance documentation comments
Frequently Asked Questions
What is the minimum ratio required for normal body text under WCAG AA?
WCAG 2.1 Level AA requires a minimum contrast ratio of 4.5:1 for standard body text below 18pt (24px) or 14pt (approx 18.66px) bold.
What constitutes large text in accessibility guidelines?
Large text is defined as at least 18pt (24px) regular weight or 14pt (approx 18.66px) bold weight, requiring a 3.0:1 ratio for AA and 4.5:1 for AAA.
What is APCA and how does it compare to WCAG 2.1?
The Advanced Perceptual Contrast Algorithm (APCA) is the perceptual model developed for WCAG 3.0. Instead of a simple mathematical luminance ratio, APCA evaluates human spatial frequency perception, accounting for font size, weight, and positive/negative polarity.
Can I simulate how color-blind users perceive my interface colors?
Yes. The integrated vision simulator transforms your color values through Protanopia (red-blind), Deuteranopia (green-blind), Tritanopia (blue-blind), and Achromatopsia (monochrome) matrices in real time.