Energy Converter

Runs locally in your browser. Nothing leaves your device.

Instantly convert energy between joules, kilojoules, kWh, calories, BTUs, therms, electronvolts and more.

Use a comma or period as the decimal separator; do not use thousands separators.

All units

SI

Microjoule (µJ)
3.6e12
Millijoule (mJ)
3,600,000,000
Joule (J)
To
3,600,000
Kilojoule (kJ)
3,600
Megajoule (MJ)
3.6
Gigajoule (GJ)
0.0036

Electrical energy

Milliwatt-hour (mWh)
1,000,000
Watt-hour (Wh)
1,000
Kilowatt-hour (kWh)
From
1
Megawatt-hour (MWh)
0.001

Calories and food energy

Thermochemical Calorie (cal(th))
860,421
International Table Calorie (cal(IT))
859,845
Thermochemical Kilocalorie (kcal(th))
860.421
Food Kilocalorie (kcal(IT))
859.845

BTU and therm

Thermochemical British Thermal Unit (BTU(th))
3,414.43
British Thermal Unit (International Table) (BTU(IT))
3,412.14
US Therm (therm(US))
0.0341214

Mechanical and CGS units

Erg (erg)
3.6e13
Inch-pound Force (in·lbf)
31,862,700
Foot-pound Force (ft·lbf)
2,655,220

Particle energy

Electronvolt (eV)
2.24694e25
Kiloelectronvolt (keV)
2.24694e22
Megaelectronvolt (MeV)
2.24694e19
Gigaelectronvolt (GeV)
2.24694e16

Energy equivalents

Ton of TNT Equivalent (t TNT)
0.000860421
Tonne of Oil Equivalent (toe)
0.0000859845

How it works

  1. 1

    Enter value and source unit

    Enter the energy value and choose the source unit from one of the six groups.

  2. 2

    Choose the target unit

    Choose the target unit, even from a different group, for example from kWh to joules.

  3. 3

    Copy the result

    Copy one or all results for further use.

Good to know

The energy converter converts directly in your browser between SI, electrical, calorie, BTU/therm, mechanical/CGS, and particle-energy units, via a common joule base. cal(th), cal(IT), BTU(IT), and BTU(th) are deliberately kept separate, since they have slightly different definitions.

Calculation runs locally in the browser. Energy and power are different quantities: kWh is energy, kW is power. Nutrition calories, technical energy, and electricity costs also have different contexts and shouldn't be mixed.

Typical use cases

Convert electricity consumption into joules

Convert kWh from electricity bills into joules or other energy units for technical calculations.

Convert nutrition figures between calories and kilojoules

Convert nutrition calories into kilojoules to compare packaging labels from different countries.

Tips for better results

Don't confuse kWh with kW

kWh is a unit of energy, kW a unit of power — both frequently appear together on electricity bills and are easily confused.

Choose the correct calorie/BTU definition

cal(th), cal(IT), BTU(IT), and BTU(th) differ slightly — choose the definition matching your source for exact results.

Features

  • Six unit groups

    SI, mechanical/CGS, electrical, calorie/nutrition, BTU/therm, and particle energy are separated.

  • Local conversion

    Calculation happens directly in the browser, without transmission to a server.

  • Separate calorie and BTU definitions

    cal(th), cal(IT), BTU(IT), and BTU(th) are clearly distinguished instead of mixed together.

Frequently asked questions

Are kWh and kW the same?

No. kWh is a unit of energy, kW a unit of power. This converter converts energy units exclusively.

Are my inputs uploaded?

No. Conversion runs entirely locally in the browser.

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