Calorific value, also known as "calorific value", is one of the important indexes of fuel quality, which refers to the heat released by fuel with unit mass (or volume) after complete combustion. Commonly used units of calorific value in industry, the units of solid or liquid calorific value are kilocalorie/kg (Kcal/kg), kilojoule/kg (KJ/kg) or megacalorie/kg (Mcal/kg) and megajoule/kg (mj/kg); The units of calorific value of gas fuel are kilocalories per standard cubic meter (Kcal/Nm3), kilojoules per standard cubic meter (KJ/Nm3) or megacalories per standard cubic meter (Mcal/Nm3) and megajoules per standard cubic meter (MJ/Nm3).

Total heat calculation formula:

Q=mq (where q stands for heat, q stands for calorific value and m stands for mass)

In recent years, with the development and mutual penetration of various disciplines, calorific value has been widely used in the field of nutrition and health care, such as low calorific value food, low calorific value potato and so on.