Accessibility Contrast Checker
Check if a color pair meets WCAG standards — free, instant.
How to Use the Accessibility Contrast Checker
- Input Foreground & Background: Enter text color HEX and background container HEX.
- Analyze Contrast Ratio: View the live calculated WCAG contrast ratio.
- Verify Compliance: Check compliance badges for Level AA and AAA standards.
Why Use This Tool
Checking whether a text and background color pair meets WCAG accessibility standards online for free is essential for building websites that are readable for everyone, including users with low vision. This tool calculates the exact contrast ratio between two colors instantly and checks it against standard AA compliance. It replaces manual luminance math with an instant, reliable calculation matching the official WCAG formula.
How It Works
This WCAG-contrast-ratio-tester calculates relative luminance for both the foreground and background colors using the official WCAG formula, then computes the contrast ratio between them, comparing the result against the standard 4.5:1 minimum threshold for AA compliance. It's a free, instant, local alternative to WebAIM's Contrast Checker for a quick accessibility check during design work.
Key Features
The color-accessibility-checker shows a live preview of your actual text and background colors together, so you can see exactly how the combination looks in addition to the calculated numeric ratio. As a UI-contrast-evaluator, results update instantly whenever you change either color, making it easy to iterate toward a compliant combination. Results now show separate pass/fail checks for WCAG AA and AAA at both normal and large text sizes, RGB and HSL values display alongside HEX, invalid color codes are caught with a clear message, and a Swap Colors button instantly flips text and background to test the reverse combination.
Common Use Cases
Web developers verify text and background color combinations meet accessibility requirements before launching a site. UI designers check contrast ratios early in the design process to avoid accessibility issues discovered later. Compliance teams audit an existing website's color choices against WCAG standards, and students learning web accessibility principles see contrast ratio calculations applied practically. Government and public sector websites verify color choices meet mandatory accessibility compliance requirements.
Tips for Best Results
If a color pair fails the AA standard, try darkening the text color or lightening the background (or vice versa) rather than changing the hue entirely — small lightness adjustments often resolve a contrast failure while keeping the overall color scheme intact. Remember that large text has a lower required ratio (3:1) than normal body text (4.5:1) under WCAG AA. Test your final color combination on an actual device screen as well, since different displays can render the same HEX values with slightly different brightness.
A Quick Note
Good contrast benefits every reader, not only those with visual impairments, since text that is easy to read reduces eye strain and improves usability across the board.
Privacy & Security
Because ToolNest processes everything entirely within your browser using client-side JavaScript, your files never leave your device. There is no server-side storage, no third-party analytics attached to your data, and no risk of a breach exposing files you processed months ago.
What is the WCAG minimum required contrast ratio for website text readability?
WCAG AA requires a minimum contrast ratio of 4.5:1 for normal text and 3:1 for large text.
How to quickly test if text foreground and background colors meet accessibility standards?
Enter both HEX colors and the tool instantly calculates the contrast ratio and shows whether it passes AA compliance.
What is the difference between WCAG AA and AAA compliance levels?
AAA is a stricter standard requiring a 7:1 contrast ratio for normal text, compared to AA's 4.5:1 requirement.
Does font size affect the required contrast ratio?
Yes, large text has a lower required minimum ratio (3:1) than normal body text (4.5:1) under WCAG AA guidelines.