kilowatt hour
Unit whose name includes an SI unit and a non-SI unit accepted for use with SI
| Name | Symbol | Quantity | Value in SI units | |
| kilowatt hour | kW h | energy | 3.6 MJ 3.6 × 106 J |
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DefinitionThe kilowatt hour, symbol kW h, is a non-SI derived unit of energy, accepted for use with the SI. One watt is equal to the power required to transfer energy at a constant rate of one joule per second. It follows that, at a constant power of one kilowatt (kW), the amount of energy transferred in one hour (h) is equal to 3.6 megajoules (MJ), or one kilowatt hour (kW h). |
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The kilowatt hour is derived from the watt (an SI coherent derived unit) and the hour (a non-SI unit accepted for use with the SI).
| power | × time | = energy | expressed in SI units |
| 1000 W | × 3600 s | = 3 600 000 W s | 3.6 MJ |
| 1 kW | × 1 h | = 1 kW h | 3.6 MJ |
The kilowatt hour is a non-SI unit of energy commonly used in household energy bills.
Metric System 