Physics:Weir formula

The Weir formula is a formula used in indirect calorimetry, relating metabolic rate to oxygen consumption and carbon dioxide 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)

Further reading

• Weir, J. B. de V. (1949). "New methods for calculating metabolic rate with special reference to protein metabolism". The Journal of Physiology 109 (1–2): 1–9. 1 August 1949. doi:10.1113/jphysiol.1949.sp004363. PMID 15394301.