How To Calculate A Current From The HP & Voltage

Horsepower is a measure of power, and voltage measures the amount of energy carried in a circuit. Current, measured in amps, represents how fast the energy moves through a circuit. For example, you might use horsepower and voltage to find the current in a motor. In order to calculate the current from the horsepower and voltage, you must also know the efficiency of the circuit.

Step 1

Multiply the amount of horsepower by 746. For example, if you had 4 hp, you would get 2,984.

Step 2

Divide the result from step one by the voltage. For example, if the voltage were 5 volts, you would get 596.8.

Step 3

Divide the efficiency by 100 to convert it from a percentage to a decimal. For example, if the efficiency were 85 percent, you would get 0.85.

Step 4

Divide the result from step 2 by the efficiency of the motor to find the current. For example, if the efficiency expressed as a decimal is 0.85 efficient, you would divide 596.8 by 0.85 to determine the current equals about 702.118 amps.