Energy Conversions

energy conversions
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Select a unit of energy

What is energy?

Energy is the ability of a physical system to carry out work. The standard derived unit of energy in the International System of Units (SI) is the joule (J). Common units of energy currently in use include kilojoule (kJ), British thermal unit (BTU), Celsius heat unit (CHU), calorie (cal), kilocalorie (kcal), erg, horsepower hour (hph), gallon-atmosphere (gal atm), watt hour (Wh), kilowatt hour (kWh), watt second (Ws), electron volt (eV), foot-pound force (ft lbf) and inch-pound force (in lbf).

Common energy conversions

  • 1 joule (J) = 1,000 millijoules (mJ)
  • 1 kilojoule (kJ) = 1,000 joules (J) = 0.001 megajoules (MJ)
  • 1 erg (erg) = 10?7 joules (J)
  • 1 British thermal unit (IT) (BTU) = 1,055.05585 joules (J)
  • 1 Celsius heat unit (CHU) = 1.8 British thermal units (BTU)
  • 1 electron volt (eV) = 1.60217656535x10?19 joules (J)
  • 1 watt hour (Wh) = 3,600 joules (J)
  • 1 kilowatt hour (kWh) = 1,000 watt hours (Wh)
  • 1 gigawatt hour (GWh) = 1,000 megawatt hours (MWh)
  • 1 kilocalorie (IT) (kcal) = 1,000 calories (IT) (cal) = 1,184 joules (J)

Subdivisions and multiples of the joule using SI prefixes

Subdivisions of the joule Multiples of the joule
Name Symbol Value Name Symbol Value
decijoule dJ 10-1 J decajoule daJ 101 J
centijoule cJ 10-2 J hectojoule hJ 102 J
millijoule mJ 10-3 J kilojoule kJ 103 J
microjoule μJ 10-6 J megajoule MJ 106 J
nanojoule nJ 10-9 J gigajoule GJ 109 J
picojoule pJ 10-12 J terajoule TJ 1012 J
femtojoule fJ 10-15 J petajoule PJ 1015 J
attojoule aJ 10-18 J exajoule EJ 1018 J
zeptojoule zJ 10-21 J zettajoule ZJ 1021 J
yoctojoule yJ 10-24 J yottajoule YJ 1024 J

Energy conversions: access links

Below you can find a list with conversions for customary energy measurement units.