Calories (cal) to kilojoules (kJ), energy conversion calculator and how to convert.
Calories to kilojoules conversion calculator
Select calorie unit type, enter the energy in calories and press the Convert button:
Small & large calories
Small calorie (cal) is the energy needed to increase 1 gram of water by 1°C at a pressure of 1 atmosphere.
Large calorie (Cal) is the energy needed to increase 1 kg of water by 1°C at a pressure of 1 atmosphere.
Large calorie is also called food calorie and is used as a unit of food energy.
How to convert from calories to kilojoules
Thermochemical calories to kJ
1 calth = 0.004184 kJ
1 kJ = 239.005736 calth
The energy in kilojoules E(kJ) is equal to the energy in thermochemical calories E(calth) divided by 239.005736:
E(kJ) = E(calth) / 239.005736
Example
Convert 300 calth to kilojoules.
E(kJ) = 300calth / 239.005736 = 1.2552 kJ
15°C calories to kJ
1 cal15 = 0.0041855 kJ
1 kJ = 238.9201 cal15
The energy in kilojoules E(kJ) is equal to the energy in 15°C calories E(cal15) divided by 238.9201:
E(kJ) = E(cal15) / 238.9201
Example
Convert 300 cal15 to kilojoules.
E(kJ) = 300cal15 / 238.9201 = 1.25565 kJ
Large/food calories to kJ
1 Cal = 4.184 kJ
1 kJ = 0.239 Cal
The energy in kilojoules E(kJ) is equal to 4184 times the energy in large/food calories E(Cal):
E(kJ) = 4.184 × E(calth)
Example
Convert 0.3 Cal to kilojoules.
E(kJ) = 4.184 × 0.3 Cal = 1.2552 kJ