Kilowatt-hour (kWh)
A unit of energy equal to one kilowatt of power sustained for one hour, or 3.6 megajoules; the standard billing unit for electricity.
The kilowatt-hour is the energy delivered by 1 kW of power over one hour. Although not an SI unit, it is universally used for electricity bills, battery capacity, EV consumption and household energy statistics.
1 kWh = 3,412.14 BTU = 860.4 kcal
1 kWh = 0.0341 therm; 1 therm = 29.307 kWh
1 kWh = 8.598 x 10⁻⁵ toe; 1 toe = 11,630 kWh
Practical scales:
- A 2 kW kettle running 3 minutes: 0.1 kWh
- A 1 kWp PV system in central Europe: about 900–1,100 kWh per year; in southern Spain 1,500–1,800
- An EV driving 100 km: about 15–20 kWh
- Average household electricity use: roughly 2,500–3,500 kWh/year in the EU, about 10,500 kWh in the US (EIA)
- One litre of diesel: about 10.0 kWh (LHV); one cubic metre of natural gas: about 10–11 kWh (HHV)
Large quantities are expressed in MWh, GWh and TWh. For fuels, kWh can be on a gross or net (HHV/LHV) basis, and EU gas bills are converted from cubic metres using a calorific value. Compare fuels in kWh with the fuel energy content calculator.
Related terms
All terms →- Watt (W)
The SI unit of power, equal to one joule per second; it measures the rate at which energy is produced, transferred or used.
- Megawatt-hour (MWh)
A unit of energy equal to 1,000 kWh or 3.6 GJ; the standard unit for wholesale electricity prices and utility-scale generation and storage.
- Power vs energy (kW vs kWh)
Power (kW) is the rate of energy flow at an instant; energy (kWh) is power accumulated over time. Capacity is measured in power, output in energy.
- Joule (J)
The SI unit of energy, work and heat: the work done by a force of one newton over one metre, or one watt sustained for one second.
- Therm
A unit of heat equal to 100,000 BTU (105.5 MJ, 29.307 kWh), used for billing natural gas to homes and businesses in the US and formerly the UK.
- Calorific value (HHV / LHV)
The heat released by complete combustion of a unit quantity of fuel; the higher (gross) value includes condensation heat of water vapour, the lower (net) value excludes it.