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, British thermal unit, Celsius heat unit, calorie, kilocalorie, erg, horsepower hour, gallon-atmosphere, watt hour, kilowatt hour, watt second, electron volt, foot-pound force and inch-pound force.
Common energy conversions
- 1 joule = 1,000 millijoules
- 1 kilojoule = 1,000 joules = 0.001 megajoules
- 1 erg = 10-7 joules
- 1 British thermal unit (IT) = 1,055.05585 joules
- 1 Celsius heat unit = 1.8 British thermal units
- 1 electron volt = 1.60217656535 × 10-19 joules
- 1 watt hour = 3,600 joules
- 1 kilowatt hour = 1,000 watt hours
- 1 gigawatt hour = 1,000 megawatt hours
- 1 kilocalorie (IT) = 1,000 calories (IT) = 1,184 joules