WCAG (Web Content Accessibility Guidelines) is an international standard for web accessibility. Color contrast is critical because over 2.2 billion people worldwide have some form of vision impairment. Sufficient contrast ensures text is readable for users with low vision, color blindness, or those viewing screens in bright sunlight. The guidelines specify minimum contrast ratios to guarantee legibility for all users.

Contrast ratio = (L1 + 0.05) / (L2 + 0.05), where L1 is the relative luminance of the lighter color and L2 is the darker. Relative luminance uses gamma-corrected sRGB values with the formula: 0.2126 × R + 0.7152 × G + 0.0722 × B. The result ranges from 1:1 (identical colors) to 21:1 (pure black on pure white). Our tool computes this in real-time using the official WCAG 2.1 algorithm.

AA (Level AA) is the widely accepted minimum standard for web accessibility, requiring a contrast ratio of 4.5:1 for normal text and 3:1 for large text. AAA (Level AAA) is the enhanced standard: 7:1 for normal text and 4.5:1 for large text. Most organizations target AA compliance as AAA can be restrictive for design. Our tool shows both levels so you can make informed decisions.

WCAG defines large text as 18pt (approximately 24px) or larger, OR 14pt (approximately 18.67px) or larger if bold. This is because larger text is inherently easier to read and therefore requires a lower contrast threshold. Headings, hero text, and prominent UI elements often qualify as "large text" under this definition.

The four main types simulated in this tool: Protanopia (red-blind, ~1% of males), Deuteranopia (green-blind, ~1% of males, most common), Tritanopia (blue-blind, very rare), and Achromatopsia (total color blindness / grayscale vision, extremely rare). Together, over 8% of men and 0.5% of women have some form of color vision deficiency. Designing with these simulations helps ensure your content is perceivable by everyone.

Three practical strategies: 1) Darken/Lighten – adjust the lightness of either the text or background while preserving hue. 2) Increase font size or weight – making text large or bold lowers the required contrast threshold to 3:1. 3) Flip the design – use the lighter color for the background and the darker for text. Our "Smart Adjustments" feature automatically suggests colors that meet AA standards while staying as close as possible to your original choice.

WCAG 2.2 (released October 2023) maintains the same contrast requirements as WCAG 2.1. However, it introduces Focus Appearance (Level AAA) which requires a minimum contrast of 3:1 for focus indicators. The core text contrast success criteria (1.4.3 for AA and 1.4.6 for AAA) remain unchanged. Future versions (WCAG 3.0) may introduce more nuanced contrast metrics.

Browser extensions can only inspect existing pages. Our tool lets you experiment and design proactively – test hypothetical color pairs, simulate color blindness on your combinations, and receive AI-powered adjustment suggestions. It's ideal for the design phase before any code is written. Plus, the preset palettes give you battle-tested, accessible color schemes you can adopt immediately.