Calories (cal) to Kilojoules (kJ) Conversion
Calories
The calorie (cal) is a unit of energy equal to exactly 4.184 joules, defined as the energy required to raise the temperature of one gram of water by one degree Celsius at 15 °C. This is the thermochemical calorie — distinct from the food calorie (written as Cal or kcal), which is 1,000 times larger. The calorie originated in 19th-century thermodynamics before the joule was established as the SI standard, and persists in chemistry, biology, and food science.
Kilojoules
The kilojoule (kJ) is a unit of energy equal to exactly 1,000 joules. It is the standard unit for expressing food energy in most countries outside the United States, where food labels display energy in both kilojoules and kilocalories (kcal). One kilocalorie equals exactly 4.184 kilojoules. In thermodynamics and chemistry, reaction enthalpies and bond energies are commonly tabulated in kilojoules per mole (kJ/mol).
| Calories (cal) | Kilojoules (kJ) |
|---|---|
| 0.1 cal | 0.0004184 kJ |
| 1 cal | 0.004184 kJ |
| 2 cal | 0.008368 kJ |
| 3 cal | 0.012552 kJ |
| 5 cal | 0.02092 kJ |
| 10 cal | 0.04184 kJ |
| 20 cal | 0.08368 kJ |
| 30 cal | 0.12552 kJ |
| 50 cal | 0.2092 kJ |
| 100 cal | 0.4184 kJ |
| 1000 cal | 4.184 kJ |
Frequently Asked Questions (FAQ)
How many kilojoules are in 1 calories?
1 calories (cal) is exactly 0.004184 kilojoules (kJ).
How do I convert calories to kilojoules?
Multiply the value in calories by 0.004184 to get the result in kilojoules. Or use the converter above — type any number and see the result instantly.