Why is the CMYK result an approximation?

CMYK is device-dependent (it describes inks on paper), while LAB is device-independent. The conversion goes through the sRGB color space as an intermediate, so the CMYK values represent a standard sRGB interpretation of the LAB color, not actual press-profiled ink amounts. For exact press color matching, use ICC profiles in a color-managed workflow.

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

Many LAB colors—especially highly saturated ones—cannot be represented in sRGB. This tool clamps each RGB channel to 0–255 before deriving CMYK. The resulting CMYK will describe the nearest printable sRGB color, not the original out-of-gamut LAB value. A warning is shown when clamping occurs.

What 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 for sRGB and the most common choice for web and display color work.

What does L*=0, a*=0, b*=0 produce in CMYK?

L*=0 is pure black, which maps to C=0, M=0, Y=0, K=100. Similarly, L*=100, a*=0, b*=0 (pure white) maps to C=0, M=0, Y=0, K=0.

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 CMYK Converter

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

Enter CIE LAB (L*, a*, b*) values and instantly get the equivalent CMYK ink percentages for print workflows.

CIE LAB Input

L* (Lightness) 53.39

a* (green → red) 80.11

b* (blue → yellow) 67.20

#D50032

CMYK Output (%)

C (Cyan)

M (Magenta)

Y (Yellow)

K (Black)

Conversion Steps

1 LAB → XYZ (D65): X=0.3082, Y=0.1693, Z=0.0459
2 XYZ → Linear RGB: Rl=0.6500, Gl=−0.0891, Bl=0.0372
3 sRGB (0–255): R=213, G=0, B=50
4 sRGB → CMYK: C=0%, M=100%, Y=77%, K=16%

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Summary

Enter CIE LAB (L*, a*, b*) values and instantly get the equivalent CMYK ink percentages for print workflows.

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 to produce linear RGB, then gamma-encoded to sRGB (0–255).
sRGB is normalized to 0–1 and converted to CMYK: K = 1 − max(R,G,B); C = (1−R−K)/(1−K); M = (1−G−K)/(1−K); Y = (1−B−K)/(1−K).
CMYK values are scaled to 0–100% and displayed. Out-of-gamut LAB inputs are clamped to the nearest sRGB color before conversion.
A live color swatch shows the approximate screen appearance of the resulting print color.

Use cases

Convert CIE LAB brand color specifications into CMYK values for print production.
Translate LAB measurements from a spectrophotometer into ink percentages for press setup.
Cross-reference LAB color science results with print-ready CMYK values.
Prepare CMYK separations from perceptually defined LAB color palettes.
Validate that a screen LAB color maps to a printable CMYK equivalent.
Bridge color management workflows between ICC profile LAB data and print ink values.
Convert CIE LAB swatches from physical color books into CMYK for offset or digital printing.
Generate CMYK starting points from LAB color targets for press proofing.

Frequently Asked Questions

Last updated: 2026-07-01 · Reviewed by Nham Vu