Energy Converter
About Calories
Large Calorie (Cal/kcal)
Used in food nutrition labels and equals 4,184 joules. When you see "Calories" on food packaging, it's actually referring to kilocalories (kcal).
Small Calorie (cal)
The scientific calorie equals approximately 4.184 joules. The exact value varies slightly depending on the specific definition used.
- Thermochemical: 4.184 J (most common scientific usage)
- 15°C calorie: 4.186 J (based on water temperature of 15°C)
- International Table: 4.1855 J (defined in international agreements)
- 20°C calorie: 4.182 J (based on water temperature of 20°C)
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 joules to calories
Joules to thermochemical calories
1 calth = 4.184 J
The energy in thermochemical calories E(calth) is equal to the energy in joules E(J) divided by 4.184:
E(cal) = E(J) / 4.184
Example
Convert 600 joules to thermochemical calories.
E(cal) = 600J / 4.184 = 143.4 calth
Joules to 15°C calories
1 cal15 = 4.1855 J
The energy in 15°C calories E(cal15) is equal to the energy in joules E(J) divided by 4.1855:
E(cal15) = E(J) / 4.1855
Example
Convert 600 joules to 15°C calories.
E(cal15) = 600J / 4.1855 = 143.352 cal15
Joules to large/food calories
1 Cal = 4.184 kJ = 4184 J
The energy in large/food calories E(Cal) is equal to the energy in joules E(J) divided by 4184:
E(Cal) = E(J) / 4184
Example
Convert 600 joules to food calories.
E(Cal) = 600J / 4184 = 0.1434 Cal
