How to Convert Amps to HP

How to Convert Amps to HP
••• Cylonphoto/iStock/GettyImages

Electric motors are often rated by one of two methods: amperes (amps) or horsepower (HP). Amperes are a measure of the rate of flow of electricity, whereas horsepower is a measurement of work divided by time, so amperes and horsepower cannot be equated or converted to one another (it would be like trying to convert pounds to miles). However, with a little math and one other variable, volts (V), the correlation between amperes and horsepower can be found.

    Determine the voltage and ampere ratings for the motor or appliance by looking for a placard on the motor listing these details. Look for numbers with a unit of A or Amp for amperes and V for volts. If no placard can be found, you can guess the voltage by how the motor is powered. If it plugs into the wall of your house, the voltage is 115 V; if it is powered by a car battery, the voltage is 12 V. For example: 5 A blender that plugs into the wall using 115 V.

    Multiply amps by volts to obtain the motor's wattage, or watts (A * V = W). Wattage is the same type of unit as horsepower, a measure of power, so it can readily be converted (like gallons to quarts). The wattage for the blender example would be 5 A * 115 V = 575 W.

    Divide the wattage by the conversion factor 746 W per HP to convert watts to horsepower. The equation would be as follows: (W) / (746 W per HP) = HP. In our example, (575 W) / (746 W per HP) = 0.75 or 3/4 HP.

    Things You'll Need

    • Pencil
    • Paper
    • Calculator (optional)


    • If the electric motor's placard lists its wattage, you can use that to proceed directly to Step 3 to lessen the workload.

Related Articles

How to Calculate KVA to MVA
What Is a 24V Power Source?
How is Wattage Calculated?
How to Size a Capacitor to an Electric Motor
How to Calculate 30 KW to Amps
How to Convert Horsepower to Foot Pounds
How to Calculate Induced Armature Voltage
How to Convert 12 Volt Alternator to 120 Volts
How to Figure kW Rating of a 3 Phase Electric Motor
How to Convert Horsepower to kWh
How to Convert Ohms to Kilowatts
How to Measure Inductance of a Coil
How to Calculate Millivolts to Amps
How to Convert HVAC Tons to Amps
How to Measure Electric Motor Torque
Energizer Watt-Hour Battery Specs
How to Find Resistance With Power & Voltage
DIY Very Simple 60-Hertz Oscillator With a Quartz Circuit
How to Convert Watts to Amps

Dont Go!

We Have More Great Sciencing Articles!