Power Converter
Watts, kW, MW, horsepower, and BTU/h.
Energy Converter
This energy converter covers joules, calories, kilowatt-hours, BTU, and electronvolts. Convert food calories to kilojoules, kWh on a power bill to BTU, or joules to foot-pounds.
Runs in your browser. Your data is not uploaded.
The same value in every unit
| Unit | Value | Copy |
|---|
How to use the Energy Converter
- Type the Value you want to convert.
- Pick the unit it is in under From, and the unit you want under To. The swap button flips them.
- The answer updates as you type. The table below it shows the same value in every other unit, each with its own copy button.
How it works
1 cal = 4.184 J (thermochemical); 1 kcal = 4,184 J 1 Wh = 3,600 J; 1 kWh = 3,600,000 J 1 BTU = 1,055.05585262 J (International Table) 1 eV = 1.602176634 × 10^-19 J result = value × from-unit (J) ÷ to-unit (J)
Examples
- 1 kWh = 3,600,000 J = 3,412.14 BTU.
- 2,000 kcal = 8,368 kJ, a typical daily food energy.
- 1 BTU = 1,055.055853 J.
- 100 kJ = 23.900574 kcal.
Kilocalorie to kilojoule conversion table
| Kilocalorie (kcal) | Kilojoule (kJ) |
|---|---|
| 50 kcal | 209.2 kJ |
| 100 kcal | 418.4 kJ |
| 200 kcal | 836.8 kJ |
| 250 kcal | 1,046 kJ |
| 500 kcal | 2,092 kJ |
| 1,000 kcal | 4,184 kJ |
| 1,500 kcal | 6,276 kJ |
| 2,000 kcal | 8,368 kJ |
| 2,500 kcal | 10,460 kJ |
| 3,000 kcal | 12,552 kJ |
Food labels in the EU and Australia show both kJ and kcal; 1 kcal is 4.184 kJ.
Energy units and their size in joules
| Unit | Symbol | Equals |
|---|---|---|
| Joule | J | 1 J |
| Kilojoule | kJ | 1,000 J |
| Calorie | cal | 4.184 J |
| Kilocalorie | kcal | 4,184 J |
| Watt-hour | Wh | 3,600 J |
| Kilowatt-hour | kWh | 3,600,000 J |
| British thermal unit | BTU | 1,055.055853 J |
| Electronvolt | eV | 1.602177 × 10^-19 J |
| Foot-pound | ft·lbf | 1.355818 J |
Calories on food labels
The "Calorie" on a US food label is a kilocalorie: 1,000 small calories, or 4.184 kJ. So a 250 Calorie snack holds 250 kcal, about 1,046 kJ. This converter writes kilocalories as kcal to keep the two apart.
Limitations
- Calories are thermochemical calories (4.184 J). The International Table calorie (4.1868 J) is 0.07% larger.
- BTU uses the International Table definition.
Frequently asked questions
How many joules are in a kilowatt-hour?
Exactly 3,600,000 J, because a kilowatt is 1,000 J per second and an hour is 3,600 seconds.
How do I convert kcal to kJ?
Multiply by 4.184. For example, 500 kcal × 4.184 = 2,092 kJ.
How many BTU are in a kWh?
One kWh is about 3,412 BTU.
Related tools
Often used together with the Energy Converter.
Temperature Converter
Celsius, Fahrenheit, Kelvin, and Rankine.
Calorie CalculatorCalculators
Daily calories to maintain, lose, or gain weight.