Contrast
An arithmetic WCAG relative luminance referee built to settle colour pairings and font choices with math rather than subjective debate.
Accessibility Engine
2026
Certified Cool
Body copy at the size this site actually uses for paragraphs, so the judgement is made on real text rather than a swatch.
6.55:1
- Body textPasses at 4.5:1
- Large textPasses at 3:1
- Borders and iconsPasses at 3:1
The challenge
Design teams frequently guess contrast compliance using eye tests or inaccurate sRGB tools that don't account for true human perceptual luminance curves, resulting in unreadable websites for millions of users with visual impairments.
The approach
We developed Contrast using the exact W3C WCAG 2.1 relative luminance formula with gamma expansion. The engine computes contrast ratios in real time, testing across normal text, large display headers, and UI components with immediate pass/fail verdict badges.
What we made
- WCAG 2.1 Arithmetic Referee
- Real-time Color Contrast Analyzer
- Interactive Type Rendering Tester
- System Color Tokens Inspector
Built with
W3C Relative Luminance Math / React 19 Hooks / CSS Color Tokens / Real-time Text Evaluator
Credits
Accessibility and systems engineering tool by Certified Cool.