What is a kWh?

You probably know that you get billed for your monthly usage of kilowatt hours of electricity. But what is kilowatt hour (kWh) anyway?

Electricity is measured in units of power called watts. Because a single watt is such a small unit of measurement, electricity is typically measured in 1000-watt units, called kilowatts.

Common devices such as light bulbs list a wattage rating that indicates how much energy is required for the device to operate. The higher the rating, the more electricity the device uses. By taking the number of watts the device uses and multiplying it by the hours the device is in use you get kilowatt hours, or kWh.

For example, burn a 100-watt light bulb for 10 hours and you will have used one kWh. (100 watts X 10 hours = 1 kWh). To see it in a different light, one kWh also is needed to burn ten 100-watt light bulbs for one hour. (10 lights @ 100 watts = 1000 watts. 1000 watts X 1 hour = 1 kWh.)