Laser beam through a lens

Hi all, I'm trying to figure out the beam diameter after a certain distance using a focusing lens and I've found this website:

Focal Spot Size Calculator | Gaussian Laser Beams

Considering reliable the results from online calculator, here my doubt: the value of the beam waist in the laser company's datasheet is usually the beam diameter at aperture w or the actual beam waist diameter w0?

Thanks! :yh: