Energy Unit Converter

Energy Unit Converter Online is online conversion tool that allows you to convert units of energy/heat/work given in one system of measurment to the other system. You can easily convert joules to calories, calories to BTU, joules to kilojoules, horsepower-hour to ergs, ergs to joules, electronvolts to joules, kilowatt hour to ergs, etc. You can easily calculate 'how many calories make one joule', 'how many joules make one kilojoule'. Additionaly, it supports atomic units of energy: electron volt conversion, hartree and rydberg energy conversion.

Accuracy number of significant decimal digits
Metric System
Joule [J] Kilojoule [kJ] Kilogram-meter [KGm] Watt hour [Wh] Kilowatt hour [kWh] Erg [erg]
Calorie [cal] * Kilocalorie [kcal]
Imperial System
foot-poundal [ft pdl] inch-pound force [in lbf] foot-pound force [ft lbf] horsepower-hour [hph] BTU**
Electronvolt [eV] Hartree [Eh] Rydberg [Ry]
*International Steam Table Calorie (1956) (calIT) equals exactly 4.1868J
**Most widely used BTU definition based on International Steam Table Calorie (1956)
Joule - Energy Unit
Unit of energy in the International System Of Units (SI) is Joule. Joule is the derived unit. Joule formula: 1 J = 1 N · m = 1 kg · m2 / s2

One joule is the amount of energy required to perform the following actions (
  • The work done by a force of one newton traveling through a distance of one meter;
  • The work required to move an electric charge of one coulomb through an electrical potential difference of one volt; or one coulomb volt, with the symbol C·V;
  • The work done to produce power of one watt continuously for one second; or one watt second (compare kilowatt hour), with the symbol W·s. Thus a kilowatt hour is 3,600,000 joules or 3.6 megajoules;
  • The kinetic energy of a 2 kg mass moving at a velocity of 1 m/s.
Joule to calorie formula: Based on International Steam Table (1956) 1 calorie is defined to be exactly 4.1868J. Ergo:

1 cal = 4.1868J => N calories = N*4.1868 J
1 J = 0.238846 cal => N joules = N*0.238846 calories.

UnitIn Joules
Metric System
Joule [J]1
Kilojoule [kJ]1000
Kilogram meter [KGm]9.80665
Watt hour [Wh]3600
Kilowatt hour [kWh]3600000
Erg [erg]1e-7
Imperial System
foot-poundal [ft pdl]0.0421401100938
inch-pound force [in lbf]0.1129848290276167
foot-pound force [ft lbf]1.3558179483314004
horsepower-hour [hph]2.6845e+6
Calories [cal]4.1868
Kilocalories [kcal]4186.8
Electronvolt [eV]1.6021765314e-19
Hartree [Eh]4.3597441775e-18
Rydberg [Ry]2.179872e-18

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