Energy Converter
Convert between energy units like Joules, Calories, and BTUs.
Runs in your browser Your input never leaves your device.
About this tool
Convert between eight energy units: joule (J), kilojoule (kJ), calorie (cal), kilocalorie (kcal), watt-hour (Wh), kilowatt-hour (kWh), electronvolt (eV) and BTU. Typical uses are electricity bills (kWh), food energy (kcal), heating (BTU) and physics (eV). Everything is converted through joules, using 4.184 J per calorie, 3,600 J per watt-hour, 1,055.06 J per BTU and 1.60218e-19 J per electronvolt. The calorie here is the small thermochemical calorie, so the nutrition label Calorie corresponds to the kilocalorie option. The result is labeled with the symbol and shows up to 8 decimals, switching to scientific notation (such as 1.602180e-19) for very small values.
How to use it
- Type the value to convert.
- Choose the From and To units.
- Read the result, which updates as you type.
- Use Swap to reverse the units or Copy to copy the result.
Example
2,000 x 4.184 = 8,368.
2000 kilocalorie to kilojoule
8368 kJ
Common problems
- Food Calories vs calories
- A food Calorie (capital C) is a kilocalorie. Choose kilocalorie for nutrition values; 'calorie' is 1/1000 of that.
- BTU values differ between sources
- There are several BTU definitions. This tool uses 1,055.06 joules.
- Joule results like 1.602180e-19
- Tiny numbers switch to scientific notation. This is expected when converting electronvolts to joules.