All conversions
| Unit | Value | Copy |
|---|---|---|
| Joule (J) | — | |
| Kilojoule (kJ) | — | |
| Megajoule (MJ) | — | |
| Calorie (cal) | — | |
| Kilocalorie (food Calorie) (kcal) | — | |
| Watt-hour (Wh) | — | |
| Kilowatt-hour (kWh) | — | |
| British thermal unit (BTU) | — | |
| Therm (US) (thm) | — | |
| Foot-pound (ft·lbf) | — | |
| Electronvolt (eV) | — |
Compare food energy, electricity usage and heating fuel by converting between scientific, nutritional and utility energy units.
How to use the Energy Converter
- 1 Type a value in either box — the conversion works in both directions.
- 2 Choose the units to convert energy from and to, or click any row in the table.
- 3 Use the swap button to reverse the conversion, then copy the result.
Formula
1 kcal (food Calorie) = 4,184 J 1 kWh = 3,600,000 J 1 BTU (IT) = 1,055.056 J
Worked examples
Input: 2,000 kcal
Result: 8,368 kJ
≈ 2.32 kWh
Input: 1 kWh
Result: 3,412.14 BTU
Calories vs. kilocalories
The "Calorie" on food labels (capital C) is a kilocalorie: 1 Cal = 1 kcal = 1,000 calories = 4,184 joules. Many countries print kilojoules alongside — multiply kcal by 4.184 to get kJ.
Comparing energy sources
Converting everything to kWh makes comparisons easy: a typical gas boiler burning 1 therm releases about 29.3 kWh of heat, while 1 kWh of electricity runs a 100 W bulb for 10 hours.
Frequently asked questions
How many joules are in a calorie?
4.184 joules (thermochemical calorie).
How many kWh is a therm?
About 29.307 kWh.
What is an electronvolt?
The energy an electron gains across 1 volt: 1.602176634 × 10⁻¹⁹ J, used in physics.
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