SI multiples of watt-hour
Multiple Name Symbol Multiple Name Symbol
100 watt-hour W·h      
101 decawatt-hour daW·h 10–1 deciwatt-hour dW·h
102 hectowatt-hour hW·h 10–2 centiwatt-hour cW·h
103 kilowatt-hour kW·h 10–3 milliwatt-hour mW·h
106 megawatt-hour MW·h 10–6 microwatt-hour µW·h
109 gigawatt-hour GW·h 10–9 nanowatt-hour nW·h
1012 terawatt-hour TW·h 10–12 picowatt-hour pW·h
1015 petawatt-hour PW·h 10–15 femtowatt-hour fW·h
1018 exawatt-hour EW·h 10–18 attowatt-hour aW·h
1021 zettawatt-hour ZW·h 10–21 zeptowatt-hour zW·h
1024 yottawatt-hour YW·h 10–24 yoctowatt-hour yW·h


The watt-hour (symbol W·h) is a unit of energy commonly used to measure electricity. One watt-hour is the amount of electrical energy equivalent to a one-watt load drawing power for one hour. For example, a 100-watt light bulb uses 100 watt-hours of energy every hour. The is commonly used in the form of the kilowatt-hour, which is 1,000 watt-hours. The watt-hour It is not an SI unit, despite being based on the watt. The SI unit of energy is the joule (J), equal to one watt-second.

In the inch-pounds unit system, a watt-hour is equivalent to 3.412 Btu.

Further reading



(2007). Watt-hour. Retrieved from http://www.eoearth.org/view/article/51cbef357896bb431f69d182


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