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Color Contrast Fixer
Suggest a foreground from a finite black/white mixing family against a fixed background, or report no attainable passing suggestion.
Opaque numeric HEX, RGB or HSL text
JSON suggestion report
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 color and Background color, then choose Target contrast ratio.
- Select Find contrast suggestion. Already-passing colors remain unchanged; unattainable targets return suggestion null. The background remains fixed.
- Select Download result to save contrast-suggestion.json. The report states the mixing direction, numerator over 255 and complete achieved ratio when a suggestion exists.
Examples
Foreground #777777 on #ffffff at 4.5:1 suggests #767676 at 2/255 toward black. The same foreground and background #777777 at 7:1 returns no suggestion.
Limitations
- At most 300 UTF-16 units per color, 511 ratio evaluations, 64 KiB JSON and 30 seconds. Inputs must normalize to opaque 8-bit RGB.
- This is a minimum fraction in the stated finite encoded-RGB black/white family, not a globally or perceptually closest color, HSL lightness search or APCA.
- A color-pair calculation is not page accessibility certification or full WCAG conformance. Unattainable states are explicit and contain no manufactured suggestion.
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