Free Color Contrast Checker
Calculate WCAG contrast ratio between two HEX colours.
Color Contrast Checker
Enter a value to begin.
How to use this color contrast checker
- Enter two six-digit colours.
- Check the inputs and preview, then use the primary action.
- Download, copy or use the result shown by the tool.
How the result is calculated
Relative luminance uses linearized sRGB, then the lighter value plus 0.05 is divided by the darker plus 0.05.
All calculation and transformation work happens in this browser tab. No entered value is sent to an Noler Tools application server.
Important limitations
Results are provided for convenience and should be checked independently before an important decision. A format or checksum result never authenticates an identity, document, account, licence, vehicle or registration.
Frequently asked questions
Is this color contrast checker free?
Yes. It is free to use and does not require an account.
Does Noler Tools save my input?
No. The input and result remain in temporary browser memory and are not uploaded or saved by this site.