Estimated energy expenditure calculator
The Mifflin–St Jeor equation estimates resting energy expenditure (REE) from age, weight, height and one of the coefficients used in the original study. An approximate activity factor produces a daily estimate. These values do not measure your metabolism or set how many calories you should eat.
Estimate energy expenditure
Educational estimate; not dietary or medical advice.
How the estimate is calculated
The original paper by Mifflin and colleagues (1990) derived and tested the equation in 498 healthy adults aged 19–78 using indirect calorimetry. Male coefficient: 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5. Female coefficient: the same expression − 161. We multiply the result by the selected activity factor for an approximate daily estimate; the factors do not measure actual activity.
Important limits
The equation predicts an average and can be inaccurate for an individual. A comparative review found meaningful errors and limitations in individual use, and some groups were underrepresented in validation studies. The activity factor adds another approximation. Do not use this result as a weight-loss, weight-gain or meal-plan target. Children, pregnant or breastfeeding people, athletes and people with medical conditions need appropriate assessment.
Frequently asked questions
Does this tell me how many calories to eat?
No. It estimates resting and approximate daily energy expenditure. Needs and nutrition goals depend on individual context and should be assessed by a qualified professional.
Is the result exact?
No. The equation was developed from adult data and predicts an average; a published review reports errors and limits in individual use. The activity factor is also approximate.
Why does the equation ask for a male or female coefficient?
The published formula has those two coefficients. It does not provide a third coefficient for other identities or situations. If neither applies, the calculator should not force a choice.
What does REE mean?
Resting energy expenditure estimates energy used by the body at rest. It is not a direct measurement and is not necessarily the same as basal expenditure measured under strict conditions.