The Weir formula is a formula used in

indirect calorimetry Indirect calorimetry calculates heat that living organisms produce by measuring either their production of carbon dioxide and nitrogen waste (frequently ammonia in aquatic organisms, or urea in terrestrial ones), or from their consumption of oxyg ...

, relating

metabolic rate Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cell ...

oxygen consumption Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well as ...

and

carbon dioxide Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...

production. According to original source, it says: :Metabolic rate (kcal per day) = 1440 (3.9 VO₂ + 1.1 VCO₂) where VO₂ is oxygen consumption in litres per minute and VCO₂ is the rate of carbon dioxide production in litres per minute. The formula can also be written for units of calories per day where VO₂ is oxygen consumption expressed in millilitres per minute and VCO₂ is the rate of carbon dioxide production in millilitres per minute. Another source gives :Energy (kcal/min) = (respiration in L/min times change in percentage oxygen) / 20 This corresponds to: :Metabolic rate (cal per minute) = 5 (VO₂ in mL/min)

References

Further reading