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 cal_th = 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 cal_th

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