Energy Converter
The joule (J) is the base energy unit here, so every one of the 8 units below, including kilojoules and calories, converts through it. Enter a value, pick your units, and the result updates instantly, all in your browser.
All energy units
| Unit | Symbol | 1 unit in joules |
|---|---|---|
| Joule | J | 1 |
| Kilojoule | kJ | 1000 |
| Calorie | cal | 4.184 |
| Kilocalorie | kcal | 4184 |
| Watt-hour | Wh | 3600 |
| Kilowatt-hour | kWh | 3600000 |
| British thermal unit | BTU | 1055.06 |
| Foot-pound | ft·lb | 1.3558 |
All energy conversions
Energy converters translate between joules, kilojoules, calories, kilocalories, watt-hours and more. The joule is the SI base unit of energy, and food calories (kcal) as well as electrical units are anchored to it.
Frequently asked questions
How many kilojoules are in a kilocalorie?
One kilocalorie, the food Calorie, equals about 4.184 kilojoules. Nutrition labels in different countries use one or the other, so this conversion comes up often.
What is a kilowatt-hour in joules?
One kilowatt-hour equals 3,600,000 joules, or 3.6 megajoules. It is the unit your electricity meter counts.
Are food Calories the same as calories?
A food Calorie with a capital C is actually a kilocalorie, equal to 1,000 small calories. UnitGlide lists both calories and kilocalories so you can pick the right scale.