Energy Converter
Convert energy between joules, calories, kilowatt-hours, BTU, electronvolts and more. Online energy unit converter.
About this calculator
Food labels use kilocalories or kilojoules, electricity bills use kilowatt-hours, heaters use BTU and physics uses joules and electronvolts. This converter links them all.
A useful anchor: 1 kilowatt-hour, one Indian electricity unit, is 3.6 megajoules, about 860 kilocalories or 3,412 BTU.
How to use it
- Type the Value.
- Choose the From Unit and To Unit.
- Press Convert.
Factors (to joules)
1 cal = 4.184 J, 1 kcal = 4,184 J, 1 Wh = 3,600 J, 1 kWh = 3,600,000 J, 1 BTU = 1,055.06 J and 1 eV = 1.602176634 × 10⁻¹⁹ J. Formula: value × from ÷ to.
Worked example
Examples
| 1 kWh (one unit) | 860.42 kcal |
| 2,000 kcal diet | 8,368 kJ |
| 1 BTU | 0.252 kcal |
| 1 kcal | 4.184 kJ |
Tips and common mistakes
- A food 'Calorie' is a kilocalorie (4.184 kJ).
- Electricity: 1 unit on your bill is 1 kWh.
- Divide kJ by 4.184 to get kcal.
- An air-conditioner's cooling is often rated in BTU/hour, which is power, not energy.
- Use scientific notation for very small values such as electronvolts.
Frequently asked questions
How many joules are in a kilocalorie?
4,184.
How many kcal are in a kWh?
About 860.4.
What is a BTU?
The heat needed to raise one pound of water by one degree Fahrenheit, about 1,055 joules.
What is an electronvolt?
A tiny energy unit, 1.602 × 10⁻¹⁹ joules, used in physics.
Is a calorie the same as a kilocalorie?
No. A food Calorie is 1,000 small calories.
What is a therm?
About 105.5 MJ, used for gas billing in the US.