How does Lab convert back to RGB?

The Lab values are run through the inverse CIELAB function to recover XYZ relative to the D65 white, multiplied by the XYZ-to-linear-sRGB matrix, then gamma-encoded and scaled to 0-255 to produce the displayable RGB color.

What does out of gamut mean?

Lab can describe colors that no sRGB monitor can show. When the computed RGB falls outside 0-255, the value is clamped into range and the tool flags it, because the on-screen color is only an approximation of the requested Lab color.

What white point is assumed?

The D65 illuminant, matching sRGB and CSS lab(), with reference white Xn=95.047, Yn=100, Zn=108.883. Using a different white point would shift the resulting RGB.

What are the valid ranges?

L* runs from 0 (black) to 100 (white). a* and b* are unbounded in theory but typically fall between about -128 and 127 for real colors; values beyond the sRGB gamut will be clamped.

Is anything sent to a server?

No. The inverse matrix and gamma math run entirely in your browser. Nothing is uploaded or logged.

What is the CIE L*a*b* to RGB Color Converter?

Free CIELAB to RGB converter. Enter L*, a*, and b* values under the D65 white point and get the equivalent sRGB color, hex code, and swatch, with an out-of-gamut warning. Runs entirely in your browser. It runs free in your browser on Gera Tools, with nothing uploaded.

CIE L*a*b* to RGB Color Converter

Name: CIE L*a*b* to RGB Color Converter
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

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Convert a CIE L*a*b* color back into a displayable sRGB value, with the matching hex code and a live swatch. This reverses the RGB-to-Lab pipeline, so you can take perceptually-defined colors and turn them into something a screen can show.

Why convert Lab to RGB?

CIELAB is the color space designers and color scientists use when they need perceptual uniformity — equal numeric distances look equal to human eyes. It is used in color palette generation, image difference metrics (Delta-E), accessibility contrast tools, and CSS lab(). But monitors speak sRGB. This converter bridges that gap: you define a color perceptually in Lab, then get the closest sRGB representation your screen can actually show.

How it works

The conversion runs the RGB-to-Lab steps in reverse:

Lab to XYZ — recover the intermediate f values, then invert the nonlinearity (cube where above the threshold, linear segment below) and multiply by the D65 white:

fy = (L* + 16) / 116
fx = fy + a*/500
fz = fy - b*/200
X = Xn * finv(fx)   Y = Yn * finv(fy)   Z = Zn * finv(fz)

XYZ to linear sRGB with the inverse matrix:

r =  3.2406*X - 1.5372*Y - 0.4986*Z
g = -0.9689*X + 1.8758*Y + 0.0415*Z
b =  0.0557*X - 0.2040*Y + 1.0570*Z

Gamma encode each linear channel and scale to 0–255:

c <= 0.0031308 ? 12.92*c : 1.055*c^(1/2.4) - 0.055

If any channel lands outside 0–255 the color is out of sRGB gamut; it is clamped and flagged.

What the axes mean

L* (0–100) — perceptual lightness. 0 is absolute black, 100 is the reference white. Doubling L* roughly doubles perceived brightness, unlike RGB where doubling a value does not.
a* — green (negative) to red (positive). Neutral grays sit near zero.
b* — blue (negative) to yellow (positive). Neutral grays also sit near zero.

Colors that are neutral (grey, white, black) always have a* and b* close to zero. Vivid, saturated colors push a* and b* to larger absolute values, and those high-chroma Lab colors are the ones most likely to fall outside the sRGB gamut.

Example

lab(55.6% 17.6 -64.4) converts back to approximately rgb(59, 130, 246) → #3B82F6.

For comparison, lab(0 0 0) → #000000 black, and lab(100 0 0) → #FFFFFF white. The conversion is most accurate in the middle of the sRGB gamut where clamping is not needed.

Out-of-gamut colors

The D65 white point is assumed, matching sRGB and CSS lab(). When Lab describes a color that no sRGB monitor can reproduce — typically highly saturated cyan-greens and some vivid blues — the RGB channels go outside 0–255. The converter clamps them to the nearest in-gamut value and flags the result so you know the displayed swatch is an approximation. If you need to show the exact color, consider a wide-gamut display mode (P3 or Rec. 2020) and CSS color() or oklch() instead of sRGB hex. All math runs in your browser — nothing is uploaded.