How to use this calculator
- Enter an amount of energy.
- Choose the from and to units.
Formula
All units are defined relative to the joule, the SI unit of energy.
1 kcal (food Calorie) = 4,184 J = 4.184 kJ
1 kWh = 3.6 MJ
1 BTU (IT) = 1,055.06 J
1 eV = 1.602176634 × 10⁻¹⁹ J
Examples
- 100 kcal × 4.184 = 418.4 kJ.
- 1 kWh ≈ 3,412 BTU.
Frequently asked questions
Is a food Calorie the same as a calorie?
No. A food Calorie (capital C) is a kilocalorie, which is 1,000 small calories. Nutrition labels in kJ divide by 4.184 to get kcal.
What is a kilowatt-hour?
The energy used by a 1,000-watt device running for one hour. It's the unit on most electricity bills.
What is a therm?
100,000 BTU, used for natural gas billing in the US and UK.