What is CIE L*a*b* color space?

CIE L*a*b* (CIELAB) is a perceptually uniform color space defined by the International Commission on Illumination. L* represents lightness (0 = black, 100 = white), a* represents the green–red axis, and b* represents the blue–yellow axis.

Why convert RGB to LAB?

CIELAB is device-independent and perceptually uniform, meaning equal numerical differences correspond to equal perceived color differences. It is widely used in color science, print production, and image processing.

Which white point / illuminant does this tool use?

This tool uses the D65 standard illuminant (the most common, representing average daylight), with the standard 2-degree observer as defined by the CIE.

What are typical ranges for a* and b*?

For colors derived from sRGB, a* and b* typically fall in the range of roughly -128 to +127. Negative a* is green, positive a* is red. Negative b* is blue, positive b* is yellow.

Is this conversion lossless?

The RGB → XYZ → LAB pipeline is mathematically reversible. However, sRGB has a smaller gamut than the full CIE color space, so LAB values will always represent colors reproducible on a standard monitor.

RGB to LAB Color Converter

Name: RGB to LAB Color Converter
Availability: InStock
Author: Nham Vu

Enter RGB values or pick a color to instantly convert to CIE L*a*b* with a live swatch and copyable output.

RGB Input

HEX (quick input)

R (red)

G (green)

B (blue)

CIE Lab* Output

#3B82F6

L* — Lightness

a* — Green–Red

b* — Blue–Yellow

Summary

Enter RGB values or pick a color to instantly convert to CIE L*a*b* with a live swatch and copyable output.

How it works

Enter R, G, and B values (0–255) in the input fields, or use the color picker.
The L*, a*, and b* values update instantly below.
The color swatch previews the exact color.
Click Copy LAB to copy the lab() CSS value, or Copy All to copy all channel values.

Use cases

Compare perceptual color differences between two colors.
Convert brand colors for use in print workflows (CIELAB is device-independent).
Feed LAB values into color-matching algorithms.
Validate color transformations in design pipelines.
Use L* to measure perceived lightness without hue bias.
Prepare colors for scientific visualization or ICC profiling.

Frequently Asked Questions

Last updated: 2026-06-10 · Reviewed by Nham Vu