UNDERSTAND THE METHOD
How to use this calculator
Enter an adult profile. Compare the standard equations or add body composition. A measured body-fat result and a BMI estimate have different uncertainty. Resting energy does not include all daily activity.
What the result can tell you
These equations estimate resting expenditure. Indirect calorimetry measures it. Cunningham 1991 uses 370 + 21.6 × fat-free mass. Cunningham 1980 uses 500 + 22 × lean body mass. The result labels show both equations separately.
Common questions
What does the RMR result include?
It estimates resting energy expenditure. Resting energy does not include all daily activity, and indirect calorimetry is the measurement method described by the source.
Why does the calculator ask for a body-composition source?
You can use a measured body-fat result, a BMI-based estimate, or standard equations. A BMI-based body-fat input has different uncertainty, and the Cunningham equations are shown separately.
Sources & limitations
Sources checked September 12, 2026. These notes identify methods and assumptions. They have not received an independent clinical review.
- Review of resting energy by age, sex category, and BMI. Confidence intervals describe group means.pubmed.ncbi.nlm.nih.gov
- Mifflin–St Jeor resting energy equation.pubmed.ncbi.nlm.nih.gov
- Revised Harris–Benedict coefficients.pubmed.ncbi.nlm.nih.gov
- Cunningham 1980 proposes 500 + 22 × lean body mass.pubmed.ncbi.nlm.nih.gov
- Fat-free mass and resting metabolic rate.pubmed.ncbi.nlm.nih.gov
- HERITAGE body-fat estimates and population differences.pubmed.ncbi.nlm.nih.gov