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Color Contrast Checker
Calculate the contrast ratio between two opaque 8-bit sRGB colors and check AA/AAA normal and large-text thresholds.
HEX color, Numeric RGB or HSL color
JSON
Browser only
Runs locally in your browser. Your files, pasted content and generated output are not uploaded. Reset clears this tool’s working data.
This tool needs JavaScript. If it does not load, refresh the page and try again.
How to use this tool
- Enter foreground and background colors as HEX or supported numeric rgb()/hsl() syntax.
- Use fully opaque colors; the tool does not infer background compositing layers.
- Select Check contrast and download contrast-report.json. Compare normal or large-text thresholds according to the actual text size.
Examples
#777777 on #ffffff has a contrast ratio of about 4.4781:1, below the 4.5:1 AA normal-text threshold.
Limitations
- Each color input is limited to 300 characters. Channels normalize to 8-bit sRGB; numeric RGB/HSL values can round during normalization.
- Named colors, CSS variables, transparency and compositing layers are not inferred. Alpha, when supplied, must be fully opaque.
- Decisions use the unrounded ratio: AA normal 4.5:1, AA large 3:1, AAA normal 7:1 and AAA large 4.5:1. Large text means at least 18 pt regular or 14 pt bold.
- This evaluates the two underlying colors only. It does not inspect a webpage, suggest replacement colors, calculate APCA or establish overall WCAG conformance.
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