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BMR and TDEE Calculator

Estimate how much energy your body uses at rest and across a typical day, using the Mifflin-St Jeor equation and a documented activity multiplier. Results are shown in both kilocalories and kilojoules.

Updated

Calculator

This equation is validated in adults aged 18 and over.

The equation has two published constant sets. Choosing neither uses their midpoint and widens the estimate.

Units
Height

Most people overestimate. If you are unsure, choosing the lower bracket gives a more useful starting point.

Runs entirely in your browser — values are never sent to a server or stored.

How we calculate it

BMR (men) = 10W + 6.25H − 5A + 5 · BMR (women) = 10W + 6.25H − 5A − 161 · TDEE = BMR × activity factor

Basal metabolic rate is the energy your body uses at complete rest to run basic functions. This calculator estimates it with the Mifflin-St Jeor equation, published in 1990 and the predictive equation most commonly recommended for adults in current dietetic practice after a systematic review found it more reliable than the older Harris-Benedict equations. In metric terms it is 10 times weight in kilograms, plus 6.25 times height in centimeters, minus 5 times age in years, then plus 5 for men or minus 161 for women. Total daily energy expenditure multiplies that basal figure by an activity factor between 1.2 for sedentary and 1.9 for extremely active — the conventional multipliers used in dietetic practice. Because the equation has only two published constant sets, selecting no sex uses the midpoint of the two, which widens the margin of error and is flagged in the result. Kilojoules are shown alongside kilocalories at 4.184 kJ per kcal, since kJ is the labeling unit in Australia, New Zealand and parts of Europe.

Important limitations

  • A predicted BMR is not a measured one. Validation studies place predicted values within roughly 10% of measured resting metabolic rate for most people, which at 1,800 kcal is a spread of about 180 kcal, and individuals fall further out in either direction.
  • Activity multipliers are broad brackets. Two people who both describe themselves as moderately active can have daily expenditure differing by several hundred calories.
  • The equation does not account for body composition. At the same height, weight, age and sex, more muscle generally means a higher BMR than predicted.
  • Thyroid conditions, some medications, significant recent weight loss, illness, pregnancy and breastfeeding all change energy needs in ways this calculation does not model.
  • These figures are general educational estimates, not a diet plan, a calorie prescription or nutrition advice for any medical condition.
  • These estimates are not an appropriate target for anyone with, or recovering from, an eating disorder. Energy needs in that situation should be set by a qualified clinician.

Frequently asked questions

Sources

This page is based on the following sources. Each was reviewed on the access date shown.

  1. A new predictive equation for resting energy expenditure in healthy individuals(opens in a new tab)

    The American Journal of Clinical Nutrition

    Peer-reviewed articlePublished February 1, 1990Accessed September 27, 2026DOI 10.1093/ajcn/51.2.241

  2. Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review(opens in a new tab)

    Journal of the American Dietetic Association

    Systematic reviewPublished May 1, 2005Accessed September 27, 2026

  3. A healthy lifestyle — WHO recommendations(opens in a new tab)

    World Health Organization

    Government health agencyAccessed September 27, 2026

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