Luminância RGB
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
Y = 0.2126R + 0.7152G + 0.0722B
About this calculator
This calculator converts RGB (Red, Green, Blue) values into perceptual luminance (Y), using the standard sRGB formula: Y = 0.2126R + 0.7152G + 0.0722B. Luminance represents human brightness perception, weighted by eye sensitivity to each color. It's widely used in digital design, color correction, and accessibility standards.
The formula coefficients simulate how the human brain processes colors. Green has the highest weight (71.52%) due to eye sensitivity to that spectral range. Red and Blue contribute 21.26% and 7.22%, respectively. The result ranges from 0 (black) to 100 (pure white), depending on input normalization.
Use this calculator to adjust interface contrasts, validate accessibility color combinations, or study color theory. For example: checking if text and background meet WCAG contrast criteria. Do not use for physical light measurements, as the formula is specific to sRGB displays.
Ensure input RGB values are normalized between 0-1 (or 0-255 in 8-bit scale). The tool doesn't process colors outside the sRGB color space, such as Adobe RGB or ProPhoto.
Frequently asked questions
What's the difference between luminance and brightness?
Luminance is a physiological calculation, while brightness is subjective perception. Luminance uses fixed weights (RGB → Y) to simulate how the brain processes light.
Should RGB values be normalized?
Yes, they must be between 0-1 (or 0-255 for 8-bit). Values outside this range may produce inaccurate results.
What is luminance used for in design?
It ensures proper contrast in interfaces, meets accessibility standards, and validates color theory in digital projects.
Why does green have higher weight in the formula?
Human eyes are more sensitive to the green spectrum, making this color contribute more to perceived brightness.
Does it work with other color spaces?
No, the formula is specific to sRGB. For spaces like Adobe RGB, you need prior conversion to sRGB.