- 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)
- Patrick Burns; Michael Snow. "Indirect Calorimetry" (PDF).
- "Techniques available for measuring energy expenditure". United Nations University.
Weir, J.B. de V., "New Methods for Calculating Metabolic Rate with Special Reference to Protein Metabolism," J. Physiol., 109: 1-9. (1949). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1392602/