Weir formula

The Weir formula is a formula used in indirect calorimetry, relating metabolic rate to oxygen consumption and carbon dioxide production. According to one source, it says:

Metabolic rate (kcal per day) = 1.44 (3.94 VO₂ + 1.11 VCO₂)

where VO₂ is oxygen consumption in millilitres per minute and VCO₂ is the rate of carbon dioxide production in millilitres per minute. The formula can also be written for units of calories per minute:

Metabolic rate (cal per minute) = 3.94 VO₂ + 1.11 VCO₂

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)