Engineering
Energy Converter
Energy is the capacity to do work. The SI unit is the joule. Nutrition uses calories, electricity bills use kilowatt-hours, heating and cooling use BTU and therms, and particle physics uses electronvolts. All are different sizes of the same underlying quantity.
51 units supported Base unit joule (J)
1 J
0.00023900574 kcal
Multiply the number of joules by 0.000239005736138 to get kilocalories. How this is calculated
About energy conversion
Energy conversion is commonly needed when nutrition labels, electricity bills, heating, and physics.
Popular conversions
Convert Joule to other energy units
1 J expressed in every other energy unit on this site.
- Joule J 1
- Kilojoule kJ 0.001
- Megajoule MJ 0.000001
- Gigajoule GJ 1e-9
- Millijoule mJ 1,000
- Microjoule µJ 1,000,000
- Nanojoule nJ 1,000,000,000
- Attojoule aJ 1e+18
- Erg erg 10,000,000
- Calorie (thermochemical) cal 0.23900574
- Kilocalorie kcal 0.00023900574
- Calorie (IT) cal(IT) 0.2388459
- Kilocalorie (IT) kcal(IT) 0.0002388459
- Megacalorie Mcal 2.3900574e-7
- Watt-hour Wh 0.00027777778
- Kilowatt-hour kWh 2.7777778e-7
- Megawatt-hour MWh 2.7777778e-10
- Gigawatt-hour GWh 2.7777778e-13
- Watt-second W·s 1
- Kilowatt-second kW·s 0.001
- Horsepower-hour hp·h 3.7250614e-7
- British Thermal Unit BTU 0.00094781712
- BTU (thermochemical) BTU(th) 0.00094845141
- MBTU (thousand BTU) MBTU 9.4781712e-7
- MMBTU (million BTU) MMBTU 9.4781712e-10
- Therm (US) thm (US) 9.4804343e-9
- Therm (EC) thm (EC) 9.4781339e-9
- Ton-hour (refrigeration) ton·h 7.8984761e-8
- Foot-pound ft·lbf 0.73756215
- Inch-pound in·lbf 8.8507458
- Foot-poundal ft·pdl 23.73036
- Kilogram-force Meter kgf·m 0.10197162
- Gram-force Centimeter gf·cm 10,197.162
- Gram-force Meter gf·m 101.97162
- Kilogram-force Centimeter kgf·cm 10.197162
- Ounce-force Inch ozf·in 141.61193
- Horsepower-hour (metric) PS·h 3.7767267e-7
- Electronvolt eV 6.2415091e+18
- Kiloelectronvolt keV 6.2415091e+15
- Megaelectronvolt MeV 6,241,509,100,000
- Gigaelectronvolt GeV 6,241,509,100
- Hartree Eh 2.2937123e+17
- Rydberg Ry 4.5874246e+17
- Ton of TNT tTNT 2.3900574e-10
- Kiloton of TNT ktTNT 2.3900574e-13
- Megaton of TNT MtTNT 2.3900574e-16
- Tonne of Oil Equivalent toe 2.388459e-11
- Barrel of Oil Equivalent bboe 1.6345576e-10
- Gigaton of TNT GtTNT 2.3900574e-19
- Fuel Oil Equivalent (kiloliter) FOE (kL) 2.487709e-11
- Fuel Oil Equivalent (US barrel) FOE (bbl) 1.5666399e-10
Complete list of energy units
All 51 units this converter supports, each stated against the joule (J).
| Unit | Symbol | System | In joules | Conversions |
|---|---|---|---|---|
| Joule | J | SI | base unit (J) | joules to kwhjoules to btu |
| Kilojoule | kJ | SI | 1 kJ = 1,000 J | kj to kcalkj to joules |
| Megajoule | MJ | SI | 1 MJ = 1,000,000 J | — |
| Gigajoule | GJ | SI | 1 GJ = 1,000,000,000 J | — |
| Millijoule | mJ | SI | 1 mJ = 0.001 J | — |
| Microjoule | µJ | SI | 1 µJ = 0.000001 J | — |
| Nanojoule | nJ | SI | 1 nJ = 1e-9 J | — |
| Attojoule | aJ | SI | 1 aJ = 1e-18 J | — |
| Erg | erg | Metric | 1 erg = 1e-7 J | — |
| Calorie (thermochemical) | cal | Metric | 1 cal = 4.184 J | calories to joulescalories to kcal |
| Kilocalorie | kcal | Metric | 1 kcal = 4,184 J | kcal to kjkcal to calories |
| Calorie (IT) | cal(IT) | Metric | 1 cal(IT) = 4.1868 J | — |
| Kilocalorie (IT) | kcal(IT) | Metric | 1 kcal(IT) = 4,186.8 J | — |
| Megacalorie | Mcal | Metric | 1 Mcal = 4,184,000 J | — |
| Watt-hour | Wh | Metric | 1 Wh = 3,600 J | — |
| Kilowatt-hour | kWh | Metric | 1 kWh = 3,600,000 J | kwh to jouleskwh to btu |
| Megawatt-hour | MWh | Metric | 1 MWh = 3,600,000,000 J | — |
| Gigawatt-hour | GWh | Metric | 1 GWh = 3,600,000,000,000 J | — |
| Watt-second | W·s | Metric | 1 W·s = 1 J | — |
| Kilowatt-second | kW·s | Metric | 1 kW·s = 1,000 J | — |
| Horsepower-hour | hp·h | Imperial | 1 hp·h = 2,684,519.5377 J | — |
| British Thermal Unit | BTU | Imperial | 1 BTU = 1,055.05585262 J | btu to joulesbtu to kwh |
| BTU (thermochemical) | BTU(th) | Imperial | 1 BTU(th) = 1,054.35026449 J | — |
| MBTU (thousand BTU) | MBTU | Imperial | 1 MBTU = 1,055,055.85262 J | — |
| MMBTU (million BTU) | MMBTU | Imperial | 1 MMBTU = 1,055,055,852.62 J | — |
| Therm (US) | thm (US) | US | 1 thm (US) = 105,480,400 J | therms to kwh |
| Therm (EC) | thm (EC) | Other | 1 thm (EC) = 105,506,000 J | — |
| Ton-hour (refrigeration) | ton·h | US | 1 ton·h = 12,660,670 J | — |
| Foot-pound | ft·lbf | Imperial | 1 ft·lbf = 1.35581794833 J | ft-lb to joules |
| Inch-pound | in·lbf | Imperial | 1 in·lbf = 0.112984829028 J | — |
| Foot-poundal | ft·pdl | Imperial | 1 ft·pdl = 0.0421401100938 J | — |
| Kilogram-force Meter | kgf·m | Metric | 1 kgf·m = 9.80665 J | — |
| Gram-force Centimeter | gf·cm | Metric | 1 gf·cm = 0.0000980665 J | — |
| Gram-force Meter | gf·m | Metric | 1 gf·m = 0.00980665 J | — |
| Kilogram-force Centimeter | kgf·cm | Metric | 1 kgf·cm = 0.0980665 J | — |
| Ounce-force Inch | ozf·in | Imperial | 1 ozf·in = 0.00706155181423 J | — |
| Horsepower-hour (metric) | PS·h | Metric | 1 PS·h = 2,647,795.5 J | — |
| Electronvolt | eV | Other | 1 eV = 1.602176634e-19 J | ev to joules |
| Kiloelectronvolt | keV | Other | 1 keV = 1.602176634e-16 J | — |
| Megaelectronvolt | MeV | Other | 1 MeV = 1.602176634e-13 J | — |
| Gigaelectronvolt | GeV | Other | 1 GeV = 1.602176634e-10 J | — |
| Hartree | Eh | Other | 1 Eh = 4.35974472221e-18 J | — |
| Rydberg | Ry | Other | 1 Ry = 2.1798723611e-18 J | — |
| Ton of TNT | tTNT | Other | 1 tTNT = 4,184,000,000 J | — |
| Kiloton of TNT | ktTNT | Other | 1 ktTNT = 4,184,000,000,000 J | — |
| Megaton of TNT | MtTNT | Other | 1 MtTNT = 4.184e+15 J | — |
| Tonne of Oil Equivalent | toe | Other | 1 toe = 41,868,000,000 J | — |
| Barrel of Oil Equivalent | bboe | Other | 1 bboe = 6,117,863,200 J | — |
| Gigaton of TNT | GtTNT | Other | 1 GtTNT = 4.184e+18 J | — |
| Fuel Oil Equivalent (kiloliter) | FOE (kL) | Other | 1 FOE (kL) = 40,197,627,984.8 J | — |
| Fuel Oil Equivalent (US barrel) | FOE (bbl) | Other | 1 FOE (bbl) = 6,383,087,908.35 J | — |
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Frequently asked questions
What is the base unit for energy?
Energy conversions on this site are calculated against the joule (J).
Which energy units can I convert?
You can convert between 51 units, including joule, kilojoule, megajoule, gigajoule, and more.
Where is energy conversion useful?
It is commonly needed when nutrition labels, electricity bills, heating, and physics.
Does this converter mix measurement systems?
The converter supports SI, Metric, Imperial, US, Other units and keeps their exact definitions separate so results stay accurate.
Related categories
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Conversion factors are based on internationally agreed unit definitions. See our methodology and sources for details on how these values are verified.