Use this color calculation to reproduce a defined sRGB compositing, blending, luminance, or accessibility-contrast operation with explicit color inputs.

Red channel

Required integer input.

Green channel

Required integer input.

Blue channel

Required integer input.

Compute WCAG relative luminance from RGB values 0-255. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Relative luminance

The resulting relative luminance returned as a number.

• Results depend on color space, transfer function, alpha convention, rounding, display profile, and the precise accessibility formula. Numeric contrast does not by itself establish readability for every user or interface state.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Verify the color-space and alpha assumptions, inspect the rendered result, and test relevant foreground, background, hover, disabled, and focus states. Pair contrast checks with broader accessibility review.

• Contrast Ratio Calculator

  Compute WCAG contrast ratio between two luminance values.

• Alpha Compositing Calculator

  Composite a source color over a backdrop color with straight-alpha source-over blending.

• Color Blend Calculator

  Blend two hexadecimal sRGB colors by interpolating their channels.