Values are processed with browser APIs and disclosed conversion formulas while the source is preserved.
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Converters
Color Contrast Checker
Calculates relative luminance and contrast ratio for foreground and background HEX colors, then reports AA and AAA thresholds for normal and large text separately. It does not replace testing the real interface.
✓ Free✓ No account✓ In-browser
QUICK ANSWER
What does this tool do?
Compare two colors against WCAG contrast ratios and text thresholds.
APPLICATION AND DECISION GUIDE
Color Contrast Checker: method and usage
Calculates relative luminance and contrast ratio for foreground and background HEX colors, then reports AA and AAA thresholds for normal and large text separately. It does not replace testing the real interface.
supported color, CSS, SVG, image, or dimension values Confirm the shape first with a small example containing no personal data.
a previewable visual value, dimension or format summary, and a copyable or downloadable result
Practical steps
- Enter foreground and background HEX colors.
- Calculate the ratio and thresholds.
- Test actual font size, weight, and state colors as well.
visual comparison across light and dark backgrounds, viewport sizes, the target app, and the source
Keep the source copy and verify output interoperability in the target application.
Suitable use cases
- Design-system color checks
- Dark-mode readability
- CTA text accessibility
LEARN THE WORKFLOW
Guides for this tool
Accessible Responsive UI: Contrast, clamp(), and Aspect Ratio
Design dark mode, fluid typography, and media placeholders with measurable constraints.
Read guide →Accessible Errors and Processing Feedback in Local Tools
Connect processing, completion, and error states to action and explanation—not color alone.
Read guide →ABOUT THIS TOOL
Frequently asked questions
What input does Color Contrast Checker accept?+
supported color, CSS, SVG, image, or dimension values Enter foreground and background HEX colors.
What does Color Contrast Checker return?+
a previewable visual value, dimension or format summary, and a copyable or downloadable result Values are processed with browser APIs and disclosed conversion formulas while the source is preserved.
How should I validate Color Contrast Checker output?+
visual comparison across light and dark backgrounds, viewport sizes, the target app, and the source
Does Color Contrast Checker send or store input on a server?+
Tool input is processed in the active tab. Saving to the Workstation or transferring to another tool is a separate choice. Consider browser extensions and shared devices separately; the privacy page explains advertising and network connections.