Main Page | See live article | Alphabetical index The kilowatt hour (symbol: kW·h) is a unit for measuring energy. It corresponds to one kilowatt (kW) of power being used over a period of one hour. The kilowatt hour is commonly used for electrical energy, since it may be easier to understand in a practical context than the proper SI unit for energy, the joule, which is a watt second (W·s). The joule is a comparatively small unit, making numbers quite large. 1 kW·h = 3,600,000 joules. The kilowatt hour is a commonly used unit of billing for electric utility companies, although many companies are moving to use the unit megajoule(MJ) instead.\n This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.