# Energy

The coherent SI unit of energy is the joule, J.

Factors in **boldface** are exact

Convert | From | To | Multiply | Std |
---|---|---|---|---|

kilojoules | kJ | J | 1000 |
3 |

megajoules | MJ | J | 1.0 x 10^{6} |
3 |

gigajoules | GJ | J | 1.0 x 10^{9} |
3 |

terajoules | TJ | J | 1.0 x 10^{12} |
3 |

watt hour | W.h | J | 3600 |
1 |

kilowatt hour | kW.h | J | 3.6 x 10^{6} |
3 |

watt second | W.s | J | 1 |
1 |

British thermal unit | Btu_{IT} |
J | 1.055056 x 10^{3} |
2 |

kilo British thermal unit | kBtu_{IT} |
J | 1.055056 x 10^{6} |
3 |

million British thermal unit | MMBtu_{IT} |
J | 1.055056 x 10^{9} |
3 |

decatherm | dT | J | 1.055056 x 10^{9} |
3 |

calorie | cal_{IT} |
J | 4.1868 |
2 |

kilocalorie | kcal_{IT} |
J | 4186.8 |
3 |

million kilocalorie | MMkcal_{IT} |
J | 4.1868 x 10^{9} |
3 |

decatherm | dT | J | 1.055056 x 10^{9} |
3 |

1: BS 350:2004 Table 37

2: BS 350:2004 Table 38

3: BS 350:2004 Section 37

Note on the calorie: The Fifth International Conference on the Properties of Steam (London, July 1956) defined the International Table calorie as 4.1868 J. Therefore the exact conversion factor for the International Table Btu is **1.055 055 852 62 kJ**. Note that the notation for International Table used in this listing is subscript ‘‘IT’’. Similarly, the notation for thermochemical is subscript ‘‘th.’’ Further, the thermochemical Btu, Btu_{th}, is based on the thermochemical calorie, cal_{th}, where cal_{th} = 4.184 J exactly.