Energy Converter
Enter an amount of energy in any common unit and see it in all the others instantly: joule (J), kilojoule (kJ), megajoule (MJ), calorie (cal), kilocalorie (kcal, the food "Calorie"), watt-hour (Wh), kilowatt-hour (kWh), British thermal unit (BTU), foot-pound (ft·lb) and electronvolt (eV). The value is converted to joules internally and then to every unit, so conversions are exact. Handy for electricity and appliances (kWh, Wh), nutrition (kcal, kJ), heating and HVAC (BTU), physics and chemistry (J, eV) and engineering (ft·lb). Everything is computed locally in your browser.
J (joule)
3,600,000
kJ
3,600
MJ
3.6
cal
860,420.65
kcal (food Cal)
860.42065
Wh
1,000
kWh
1
BTU
3,412.1416
ft·lb
2,655,223.7
eV
2.2469e+25
How to use
- Type an energy value.
- Pick the unit you entered it in.
- Read the value in every other unit and copy whichever you need.
Frequently asked questions
- How many joules are in a kilowatt-hour?
- 1 kWh = 3,600,000 J = 3.6 MJ, because 1 watt for 1 hour is 3,600 joules and a kilowatt is 1,000 watts. It's the unit your electricity meter counts.
- Is a food Calorie the same as a calorie here?
- A food "Calorie" (capital C) is a kilocalorie: 1 kcal = 1,000 cal = 4,184 J. So a 100-Calorie snack is 100 kcal ≈ 418 kJ. This tool lists both cal and kcal.
- How do BTU and kWh relate?
- 1 kWh ≈ 3,412.14 BTU, and 1 BTU = 1,055.06 J. BTU is common for heating, air-conditioning and gas appliances in the US.
- What is an electronvolt?
- An electronvolt (eV) is a tiny energy unit used in physics: 1 eV = 1.602176634 × 10⁻¹⁹ J, the energy an electron gains crossing a 1-volt potential difference.
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