OK, like many of you I recently purchased an M12V router from Amazon at a good price. I've run a lot of material with it and it seems to be a solid performer. It's classed as a 3 1/4hp machine. The spec sheet gives the rating as: "15 Amp motor (3.25 Horsepower), heavy-duty power for fast, clean cuts".
So, seeing as 1 hp = 746 Watts = 6.78 Amps at 100% efficiency, how does the M12V get a 3.25hp rating when you calculate 15A @ 110 Volts, get 1650W, divide that by 746W and yield 2.21hp at 100% efficiency?
I checked PC and they use the same rating on their 3.25hp routers.