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How to Calculate Kilowatts Given Voltage & Amperage

Scientists, engineers and electricians have a variety of units of measurement they can use to describe aspects of electrical flow. The most common unit of current, which is the amount of electrons which are moving through a wire, is the ampere, or (A). Voltage is a measure of the potential work which can be done by electricity and is measured in volts (V). Finally, the watt (W) is the unit of power which describes the amount of work done by an electric current, and a kilowatt (kW) is 1,000 watts. You can calculate the kW of work done by a given amperage and voltage using a simple equation.

Things You'll Need

Calculator

Instructions

- 1
  Multiply the amperage (in units of amps) by the voltage (in units of volts). The result of this calculation is the electrical power of that system, in units of watts. For example, if you have an appliance which uses 5 amps of current and it is plugged into a 120-volt outlet, multiply 5 by 120 to obtain 600 watts.
- 2
  Divide the result of your previous calculation by 1,000. Since there are 1,000 watts in a kilowatt, this is the conversion factor between the two.
- 3
  Report or record the outcome of your last calculation as the power of your system, in units of kilowatts. In the case of the example, report the power of the appliance as 600 divided by 1000 or 0.6 kW.

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