Relative Luminance Calculator
Calculate WCAG relative luminance and contrast against white or black.
About This Tool
Calculate WCAG relative luminance for a color and compare it against white and black backgrounds.
Use it to reason about contrast, foreground choices, chart colors, and accessibility-sensitive UI states.
Relative luminance
0.1532
Against white
5.17:1
Against black
4.06:1
How to Use
- 1
Enter the values you need or paste your text into the input area.
- 2
Adjust any options, units, or settings for your exact use case.
- 3
Review the result and copy it into your document, workflow, or next task.
Features
Instant Results
Outputs update directly in the browser as you enter values.
Browser-Based Processing
Your inputs are handled locally and are not uploaded for calculation.
Simple Inputs
Clear fields and readable outputs keep repeat tasks fast.
Free to Use
Use the tool immediately with no sign-up or installation.
Common use cases
- ›Choose whether white or black text works better on a color.
- ›Check luminance before building a palette.
- ›Record contrast values for accessibility notes.