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Energy Converter Guide
Convert energy between joules, calories, kilocalories, watt-hours, kilowatt-hours, and BTU — useful for food, electricity, and heating. Enter a value and pick the units.
1 cal = 4.184 J · 1 kcal = 4184 J · 1 kWh = 3.6 MJ · 1 BTU = 1055 J · 1 food Calorie = 1 kcal.
How Many Joules Are in a Calorie?
Each unit is defined against the joule. One small calorie is 4.184 joules, and one kilocalorie (a food Calorie) is 4184 joules. To convert kcal to kilojoules, multiply by 4.184.
Quick Reference Table
| From | To | Multiply by |
|---|---|---|
| Kilocalories | Kilojoules | 4.184 |
| Kilowatt-hours | Megajoules | 3.6 |
| BTU | Joules | 1055.06 |
| Calories | Joules | 4.184 |
Related: TDEE Calculator, Power Converter, and Pressure Converter.
Frequently Asked Questions
How many joules are in a calorie?
4.184 joules.
How many joules are in a kWh?
3,600,000 joules.
Calorie vs food Calorie?
A food Calorie is a kilocalorie — 1000 small calories.
How many joules are in a BTU?
About 1055 joules.
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