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.

CIE L*a*b* to RGB Color Converter

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.

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.

Example

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

Notes

The D65 white point is assumed, matching sRGB and CSS lab(). Out-of-gamut colors are clamped into range and marked, since a monitor cannot display them exactly. All math runs in your browser — nothing is uploaded.