Weir formula explained

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:^[1]

Metabolic rate (kcal per day) = 1.440 (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^[2]

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. . New methods for calculating metabolic rate with special reference to protein metabolism . The Journal of Physiology . 1949 . 1 August 1949 . 109 . 1–2 . 1–9 . 1392602 . 15394301 . 10.1113/jphysiol.1949.sp004363.

Notes and References

1. Web site: Patrick Burns. Michael Snow. Indirect Calorimetry.
2. Web site: Techniques available for measuring energy expenditure. United Nations University.