As has been said, guessing won't give you figures. However... if you can light incense, a candle, melt holes in carpet/furniture and with some perseverance set dark paper on fire, you at least have a fair amount of power. I can do all of the above with my 1.6W blue from laserbtb, and I don't have the steadiest of hands. It gets interesting with the beam "unfocussed" - at infinity it'll still melt tape, light matches and turn carpet to cinders... as I have rather inadvertently discovered lol. A beamstop is a MUST with these lasers, else you'll burn something precious or even cause a fire.
I don't have an LPM partly because of cost but partly because of what Livinloud says - if I were to LPM my lasers and they were underspec I'd be pretty miffed. At least without knowing the exact figures I don't obsess about it and since the lasers meet my expectations and do what is generally accepted for their spec, I'm not too fussed at the moment. Sometimes ignorance is bliss. As long as I can photograph the beams and frazzle stuff when I need my spirits lifting all's good.