Kilowatt hour (kWh)

In short: A kilowatt hour is the energy a device with 1,000 watts of power uses in one hour. It is the billing unit for electricity, gas and heat.

In more detail: Watts measure power at a moment, kilowatt hours measure energy over time. A 2,000 W kettle running for 3 minutes uses 2,000 W × 0.05 h = 100 Wh = 0.1 kWh. At 33 ct per kWh that costs 3.3 cents.

Our context: The energy and utility cost calculator projects appliance costs from watts and hours per day to a whole year.

In Depth

• Formula: kWh = watts × hours ÷ 1,000.
• Annual cost of an appliance: watts × hours per day × 365 ÷ 1,000 × price per kWh.
• Standby: 10 W around the clock is 87.6 kWh a year, about €29 at 33 ct.
• Conversion: 1 kWh = 3.6 megajoules = 860 kcal.
• Gas: Gas meters measure cubic metres. The provider converts to kWh using calorific value and state number for gas.

See also: Electricity price: base price and unit price, Standby consumption