WCAG Color Contrast Checker
Test color contrast ratios against WCAG 2.1 / 2.2 AA and AAA accessibility standards.
TL;DR: WCAG Color Contrast Checker calculates luminance contrast ratios between foreground and background colors.
Large text sample (24px bold)
| Requirement | Result |
|---|---|
| Normal text — AA (4.5:1) | Pass |
| Normal text — AAA (7:1) | Pass |
| Large text — AA (3:1) | Pass |
| Large text — AAA (4.5:1) | Pass |
What Is the WCAG Color Contrast Ratio?
The Web Content Accessibility Guidelines (WCAG 2.1/2.2) define contrast ratio as the relative luminance difference between foreground text and its background color, ranging from 1:1 (no contrast) to 21:1 (maximum black-on-white contrast). Level AA requires 4.5:1 for normal text and 3:1 for large text; Level AAA requires 7:1 for normal text.
How to Use the WCAG Color Contrast Checker
Our WCAG Color Contrast Checker is engineered to run 100% locally in your web browser with zero external API latency and complete client-side security.
- Enter or pick your Foreground (Text) color (HEX, RGB, or HSL).
- Enter or pick your Background color.
- Review the calculated Contrast Ratio (e.g. 7.42:1).
- Check compliance badges for WCAG AA and AAA across Normal Text, Large Text, and UI Components.
Key Capabilities & Best Practices
- Instant In-Browser Execution: Zero network round-trips or server latency; calculations and processing update in real time.
- Fully Responsive & Mobile Optimized: Designed with accessible touch controls and fluid typography across desktop, tablet, and mobile screens.
- Standardized Formats: Generates standards-compliant outputs ready for professional commercial, retail, development, or personal workflows.
100% Client-Side Privacy Guarantee
All calculations, cryptographic operations, file sanitizations, and document renderings occur 100% locally on your device. Your passwords, invoices, camera feeds, and files are never transmitted to remote servers.
Frequently Asked Questions
- The WCAG contrast ratio measures the brightness difference between text and its background to ensure legibility for users with visual impairments.
- Level AA is the legal standard (requires 4.5:1 for normal text and 3:1 for large text); Level AAA is the highest accessibility tier (requires 7:1 for normal text and 4.5:1 for large text).
- Large text is defined as at least 18pt (24px) regular weight or at least 14pt (18.66px) bold weight.
- Yes. Under WCAG 2.1 Level AA (Criterion 1.4.11), non-text UI elements like buttons, inputs, and functional icons require at least a 3:1 contrast ratio.
- Relative luminance ($L$) is calculated by linearizing sRGB values and weighting red (0.2126), green (0.7152), and blue (0.0722) components to match human eye sensitivity.
- Failing colors make content difficult to read for people with low vision or color blindness and can cause accessibility legal compliance violations.
- No. The mathematical ratio $(L_1 + 0.05) / (L_2 + 0.05)$ divides the lighter color by the darker color, producing the exact same ratio regardless of which is text or background.
- Yes. Our tool accepts HEX color codes, RGB integers, and HSL values with interactive color pickers.
Embed This Tool
Add the live WCAG Color Contrast Checker to your own website with this lightweight responsive iframe:
<iframe src="https://nexlove.org/embed/wcag-contrast-checker.html" width="100%" height="650" style="border:1px solid #e2e8f0;border-radius:12px" title="WCAG Color Contrast Checker — NexLove.org" loading="lazy"></iframe>