To find the formula for Horsepower is simple .... volts x amps =watts /746 = HP that is simple and easy . Now the hard one , what is the simple formula for the RPM's of a DC electric motor ? The RPM of a AC motor is... volts x hertz = unloaded RPM . But what is the RPM of a DC motor ? Loaded motor or unloaded motor . Just in case , in general you can see the poles in a DC motor . Most of our motors are 4 pole but they are painted , no tags , and over volted . The controllers are mainly 120 volts and 480 amps or 142 volts and 900 amps . The formula should work on any motor , from 165 MPH DC Plasma to my monster road course car to a scooter .