What is the valid range for L*, a*, and b*?

L* ranges from 0 (pure black) to 100 (pure white). a* and b* are theoretically unbounded but typically range from about −128 to +127 for colors within the sRGB gamut. Values outside these ranges are accepted and the resulting RGB is clamped to 0–255 before HWB conversion.

What happens when a LAB color is outside the sRGB gamut?

Many highly saturated LAB colors cannot be represented in sRGB. This tool clamps each R, G, B channel to 0–255, which produces the nearest displayable color. The HWB output reflects the clamped color, not the original out-of-gamut LAB value.

Which illuminant does this tool use?

D65 (standard daylight, 6500 K) with reference white Xn=0.95047, Yn=1.00000, Zn=1.08883. D65 is the default illuminant for sRGB and the most common choice for web and display work.

What is HWB and how is it different from HSL?

HWB stands for Hue, Whiteness, Blackness. Unlike HSL, which uses Saturation and Lightness, HWB describes colors by how much white and black are mixed into a pure hue. It is part of CSS Color Level 4 and is supported in all modern browsers using the hwb() syntax.

What does L*=53.39, a*=80.11, b*=67.20 convert to?

Those LAB values correspond approximately to sRGB red (255, 0, 0), which converts to hwb(0 0% 0%) in HWB notation.

Does this tool send any data to a server?

No. All conversion math runs entirely in your browser using JavaScript. No data is transmitted anywhere.

LAB to HWB Converter

Name: LAB to HWB Converter
Availability: InStock
Author: Nham Vu

Enter CIE LAB (L*, a*, b*) values and instantly get the equivalent HWB color with a live preview swatch.

CIE LAB Input

L* (Lightness) 53.39

a* (green → red) 80.11

b* (blue → yellow) 67.20

rgb(255, 0, 0)

HWB Output

Hue (°)

Whiteness (%)

Blackness (%)

Conversion Steps

1 LAB → XYZ: X=0.4124, Y=0.2126, Z=0.0193
2 XYZ → RGB: R=255, G=0, B=0
3 RGB → HWB: hwb(0 0% 0%)

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Summary

Enter CIE LAB (L*, a*, b*) values and instantly get the equivalent HWB color with a live preview swatch.

How it works

Enter L* (0–100), a* (−128 to +127), and b* (−128 to +127) using the number inputs or sliders.
LAB is converted to XYZ tristimulus values using the inverse CIE f() function and D65 reference white (Xn=0.95047, Yn=1.00000, Zn=1.08883).
XYZ is multiplied by the inverse sRGB matrix and gamma-encoded to produce clamped sRGB (0–255).
RGB is converted to HWB: Whiteness = min(R,G,B)/255, Blackness = 1−max(R,G,B)/255, Hue via the standard HSV hue formula.
The HWB output — Hue (°), Whiteness (%), and Blackness (%) — updates instantly.
A color swatch previews the resulting color; click the copy buttons to grab the hwb() or rgb() CSS string.

Use cases

Translate perceptual LAB color specs into CSS-ready HWB values.
Convert ICC profile LAB measurements into hwb() strings for modern stylesheets.
Build HWB palettes from perceptually uniform LAB color steps.
Verify that a LAB color is within the sRGB gamut before using it in web design.
Cross-reference CIE LAB paint or ink definitions with HWB for CSS Color Level 4.
Bridge color science workflows with browser-native hwb() color values.
Generate HWB values from spectrophotometer LAB readings.
Quickly check the hue, whiteness, and blackness of any CIE LAB color.

Frequently Asked Questions

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Last updated: 2026-05-28 · Reviewed by Nham Vu