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Palette Contrast Ratio Grid
Download every pairwise contrast ratio and four complete AA/AAA threshold matrices for a bounded opaque color palette.
Opaque numeric color text, one per line
Complete JSON ratios and four threshold matrices
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 Opaque palette colors, one per physical line. Blank trimmed lines are ignored.
- Select Build contrast grid.
- Download contrast-grid.json; the complete matrix is in the file even when a preview is bounded.
Examples
Black against white gives ratio 21; every diagonal ratio is 1, and swapping the pair leaves the ratio unchanged.
Limitations
- 1 through 64 colors, 300 UTF-16 units per original physical line, 20,000 input units, 64 KiB input, at most 4,096 ordered pairs, 5 MiB report and 30 seconds.
- Numeric opaque colors only. Thresholds are 4.5/3 for AA normal/large and 7/4.5 for AAA; ratio values are not rounded before decisions.
- No alpha compositing, APCA, whole-page conformance audit, nearest-color adjustment, image sampling or calibrated print/profile claim.
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