Contrast Checker
Validate color accessibility against WCAG AA and AAA standards
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⚙️ How It Works
Select your desired foreground (text) and background colors using HEX, RGB, or the visual picker. The tool algorithmically computes the relative luminance and instantly displays the exact contrast ratio alongside definitive Pass/Fail grades for WCAG standard levels.
❓ Frequently Asked Questions
What are WCAG AA and AAA standards?
WCAG AA requires a baseline contrast ratio of at least 4.5:1 for normal text and 3:1 for large text. The stricter AAA rating requires a 7:1 ratio for normal text and 4.5:1 for large text, ensuring maximum legibility for visually impaired users.
What qualifies as 'Large Text'?
Under WCAG guidelines, text is usually considered 'large' if it is approximately 18pt (24px) or larger, or 14pt (18.5px) and bold.
Why is an accessible contrast ratio important?
High color contrast is essential for users with visual impairments, color blindness, or those reading screens in tough lighting environments (like bright sunlight). It is also a fundamental ranking factor for modern SEO and usability.
Does the Contrast Checker work offline?
Yes, the Contrast Checker is fully functional offline. Because this tool runs entirely in your browser, no data is ever uploaded to external servers. Once the page is loaded, you can seamlessly continue using it without an active internet connection. You can also install Knicknaks as a Progressive Web App (PWA) for native-like offline access.