Energy Converter
Convert joules, kilojoules, calories, kilocalories, kilowatt-hours, BTU and therms.
About the Energy Converter
The joule is the SI unit of energy. Food energy is labelled in kilocalories (shown as “Calories” in the US) or kilojoules: 1 kcal = 4.184 kJ.
Electricity is billed in kilowatt-hours: 1 kWh is 3.6 million joules. Heating fuel in the US is often priced per therm, 100,000 BTU.
The formula
Result = Value × (size of the “from” unit ÷ size of the “to” unit)
- 1 J
- 1 J
- 1 kJ
- 1,000 J
- 1 cal
- 4.184 J
- 1 kcal
- 4,184 J
- 1 Wh
- 3,600 J
- 1 kWh
- 3,600,000 J
Every energy unit is converted through joule using its exact definition.
Common conversions
| From | To |
|---|---|
| 1 kcal | 4.184 kJ |
| 1 kJ | 0.2390057361 kcal |
| 1 kWh | 3,412.141633 BTU |
| 1 BTU | 1.055055853 kJ |
| 1 kWh | 3,600 kJ |
| 1 thm | 29.30011111 kWh |
How to read your result
- The table shows your energy in every unit.
Worked example
Example: 110 kilocalorie (food calorie) = 460.24 kJ
- Inputs: Value: 110; From: Kilocalorie (food Calorie) (kcal); To: Kilojoule (kJ).
- Formula: Result = Value × (size of the “from” unit ÷ size of the “to” unit)
- Multiply by the number of kJ in one kcal 110 × 4.184 = 460.24 kJ
- Result: 110 kilocalorie (food calorie) = 460.24 kJ
- 1 kcal = 4.184 kJ
- 1 kJ = 0.2390057361 kcal
Questions people ask
Is a food Calorie the same as a calorie?
No. A food Calorie (capital C) is a kilocalorie, 1,000 small calories.
How many BTU is a kilowatt-hour?
About 3,412.14 BTU.