REE Calculator (Resting Energy Expenditure, kcal & kJ)

Calculate resting energy expenditure (REE) in kcal or kJ per day from sex, age, weight and height with Mifflin-St Jeor, or from body fat percentage.

Disclaimer: This calculator provides an estimate only and is not medical advice or a diagnosis. Do not use it to set calorie intake for children/adolescents, pregnancy or breastfeeding, eating disorders, or medical conditions without guidance from a qualified clinician or registered dietitian.

Resting Energy Expenditure Prediction Equations

This calculator reports published adult resting-energy prediction equations. It does not measure REE. In comparison mode it reports each result and the descriptive minimum-to-maximum span; it does not average the equations or present the span as a confidence interval.

Mifflin - St Jeor, male = 10 \times W + 6.25 \times H - 5 \times A + 5; Mifflin - St Jeor, female = 10 \times W + 6.25 \times H - 5 \times A - 161; Revised Harris - Benedict, male = 88.362 + 13.397 \times W + 4.799 \times H - 5.677 \times A; Revised Harris - Benedict, female = 447.593 + 9.247 \times W + 3.098 \times H - 4.330 \times A; Cunningham 1991 = 370 + 21.6 \times FFM; Cunningham 1980 = 500 + 22 \times FFM; Activity - adjusted estimate = resting estimate \times selected multiplier; kJ / day = kcal / day \times 4.184

W = weight in kilograms
H = height in centimeters
A = age in completed years
FFM = fat-free mass in kilograms, calculated here as weight*(1-body-fat fraction)

Mifflin-St Jeor was derived in healthy adults ages 19–78; predictions beyond that age range are extrapolations. The revised Harris-Benedict equation (Roza and Shizgal, 1984) uses different coefficients and is shown only as a comparison. Cunningham’s distinct 1980 and 1991 equations depend on body-composition input; differences among DEXA, BIA, skinfolds, and other methods carry into the estimates.

Activity Multipliers

The optional multipliers from 1.00 to 1.725 are broad heuristics. Multiplying a resting estimate does not measure total daily energy expenditure and is not the same as using the current DRI EER equations.

How to Interpret the Results

Select one equation when its required inputs fit your purpose. Comparison mode shows how the published predictions differ for the same inputs; the calculator does not imply that their average is validated or more accurate. Indirect calorimetry measures resting expenditure more directly.

This adult calculator is not a calorie prescription, diagnosis, or minimum-intake tool. Pregnancy, breastfeeding, eating-disorder history, illness, and medications that affect energy needs require individualized guidance from a qualified clinician or registered dietitian.