How to Calculate DC Motor Amperage

James Stevens

Amperage is the amount of current an electrical item, such as a direct current (DC) motor, draws from a power supply. The greater the amperes drawn from the power supply, the more powerful the motor. DC motors have a label on the side of the casing, which often indicates the voltage and the amperes. However, sometimes the motor label only shows voltage and wattage, so you need to calculate the amperes.

Use a calculator to work out amperage.

Step 1

Look on the label of the DC motor. Write down the voltage and the wattage on a sheet of paper. For example, it may say 110 volts and 1,000 watts – or 1 kilowatt. However, if one of the numbers has a “V” before or after it instead of a word, it means volts. If the other number has a “VA,” or “W” before or after the number it means wattage.

Step 2

Enter the wattage into a calculator. Press the “Divide” button and then enter the voltage you wrote down.

Step 3

Press the “Equal” button. The result displayed is the DC motor’s amperes. Wattage divided by voltage equals amperes.