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How to Calculate the KWH of a Home Appliance

Electric companies determine how much you owe for electricity use by determining the number of kilowatt-hours you used during the month and assigning a set rate. Utility bills can get expensive, but you can cut your electricity use if you know which devices are consuming the most power. Determining the kilowatt-hour -- kWh -- of an appliance lets you figure how much electricity that device uses over a set period.

Instructions

- 1
  Locate the wattage rating on the device. If you don't know it, you can find the current draw in amps on the device's label and multiply it by 120, the standard household voltage. Heavy-duty devices like refrigerators, laundry machines or hot-water heaters may use 240-volt outlets.
- 2
  Multiply it by the number of hours you use the device during the day. For example, if you have a 40-watt light bulb that stays on 8 hours per day, it uses 320 watt-hours daily.
- 3
  Multiply by the number of days in a month: in a 30-day month, assuming you use the light bulb regularly for the same period each day, uses 960 watt-hours.
- 4
  Divide this number by 1,000 to determine the number of kilowatt-hours; in this case, 0.96 kWh.

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