Calories to Kilojoules Converter
Convert calorie to kilojoule instantly. Type a value below — the result updates as you type.
When you need to convert calorie to kilojoule
Energy conversions appear on nutrition labels, utility bills and appliance specs, letting you compare food energy, electricity use and heating output on a common scale.
Typical values: 0.5 cal is about 0.0021 kJ, and 100 cal works out to roughly 0.4184 kJ. Because the ratio is fixed at 0.0042, you can scale any amount linearly — doubling the calories doubles the kilojoules.
Food packaging, power meters and heating equipment each prefer different energy units, so converting makes them directly comparable.
How to convert calorie to kilojoule
One calorie equals 0.0042 kilojoules. To convert, multiply the number of calories by 0.0042:
kilojoules = calories × 0.0042
For example, 10 calories × 0.0042 = 0.0418 kilojoules.
Calories to kilojoules conversion table
| Energy (cal) | Kilojoules (kJ) |
|---|---|
| 1 cal | 0.0042 kJ |
| 2 cal | 0.0084 kJ |
| 3 cal | 0.0126 kJ |
| 5 cal | 0.0209 kJ |
| 10 cal | 0.0418 kJ |
| 20 cal | 0.0837 kJ |
| 50 cal | 0.2092 kJ |
| 100 cal | 0.4184 kJ |
FAQ
How many kilojoules are in a calorie?
One calorie = 0.0042 kilojoules.
How do I convert kilojoules back to calories?
Divide by 0.0042, or use the kilojoules to calories converter.