Processing boundary
Input is processed only in the active browser tab's memory and is not sent to a ByteQuant server.
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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
Persistent storage
Input and output are not stored. The optional usage counter keeps only tool identity and count, never content.
Verification
Output comes from disclosed rules or browser APIs and needs independent review before high-impact use.
A result in three steps
- 01
Enter foreground and background HEX colors.
- 02
Calculate the ratio and thresholds.
- 03
Test actual font size, weight, and state colors as well.
When is this tool useful?
- ✓ Design-system color checks
- ✓ Dark-mode readability
- ✓ CTA text accessibility
Important limitation
Automated output is a preliminary assessment. Do not use it alone for legal, financial, medical, or security-critical decisions.
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 →ABOUT THIS TOOL
Frequently asked questions
Does this tool send input to a server?+
No. Processing runs in this browser tab. Data leaves the page only when you choose to copy or download the result.
Is the result definitive?+
The tool produces consistent output from disclosed rules and browser APIs, but context, data quality, and method limitations can affect it. Verify high-impact decisions.
Is input saved?+
No. Tool input is not persisted. With consent, only tool identity and usage count may be kept on this device for personal shortcuts.