this guy is bang on..
the formula is Power(watts) = Volts x Amps
actually P(w)=E(v) x I(a)...
watts, amps, volts.. are the units of measurement..
so we know our volts 120... we know our amps 20 or 15 on a lower case scenerio but we're gonna go with 20..
P=120x20
P=2400 watts on that...