Estimate resting energy expenditure
Enter your age, height and weight. The tool calculates a predicted resting energy expenditure using the Mifflin–St Jeor equation. It cannot directly measure basal metabolism or tell you how many calories to eat.
Worked example
For a 30-year-old adult using the male equation at 70 kg and 170 cm, the estimate is 10 × 70 + 6.25 × 170 − 5 × 30 + 5 = 1,617.5 kcal/day, displayed as about 1,618. Under the female equation, the same measurements give 1,451.5 kcal/day, displayed as about 1,452. This difference comes from the model coefficient, not from a measurement of the person.
BMR versus resting energy expenditure
Searches often call this a “BMR calculator,” but the original Mifflin–St Jeor study derived an equation for resting energy expenditure (REE), measured by indirect calorimetry. A predicted REE is not an individually measured basal metabolic rate (BMR). We show the distinction so the formula and result have the right label. The study included healthy adults aged 19–78; this tool restricts the entered age to that research range.
What this result can and cannot tell you
The estimate is based on entered age, weight, height and a model coefficient for the male or female group in the original study. It does not account directly for body composition, medications, illness, pregnancy or an individual’s measured metabolism. The original model’s sex coefficients are limited; if the binary choice is unsuitable for your circumstances, this result may be a poor fit and an individualized assessment is more appropriate.
REE represents energy use at rest. It does not include the full cost of activity and should not be interpreted as a personal daily calorie target, weight-loss prescription or diagnosis. For health decisions, discuss the result with a qualified clinician or dietitian. The NIDDK Body Weight Planner is a separate planning tool that considers additional inputs; do not substitute its output for this equation.
Unit checks and rounding
Metric inputs use kilograms and centimeters. Imperial inputs are converted using 1 kg ≈ 2.2046226218 lb and 1 inch = 2.54 cm, then the same equation is applied. The calculation uses the converted full-precision values, while the breakdown rounds inputs for readability. Changing units after entering values converts the visible inputs. Check that your height is in centimeters or inches as shown and that your weight is in kilograms or pounds before calculating.
See our calculation standards for our approach to assumptions, limitations and corrections.