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BMR Calculator

Find your basal metabolic rate, the calories your body burns at complete rest, with the three best-known equations, and see your daily calorie needs for each activity level.

Units
Sex
years
cm
kg
BMR (Mifflin–St Jeor)
1,320 kcal
Harris–Benedict (revised 1984)
1,384 kcal
Harris–Benedict (original 1918)
1,394 kcal
Calories a day by activity (Mifflin–St Jeor BMR × activity factor)
ActivityFactorCalories a day
Sedentary (desk job, little exercise)× 1.21,584 kcal
Light (exercise 1–3 days/week)× 1.3751,815 kcal
Moderate (exercise 3–5 days/week)× 1.552,046 kcal
Very active (hard exercise 6–7 days/week)× 1.7252,277 kcal
Athlete / physical job + training× 1.92,508 kcal

An estimate for healthy adults, not medical advice. If you're pregnant, have a health condition or take medication, ask a doctor or dietitian first.

The equations

Weight in kg, height in cm, age in years. The result is in kilocalories (kcal) a day.

  • Mifflin–St Jeor (1990): men 10 × weight + 6.25 × height − 5 × age + 5; women 10 × weight + 6.25 × height − 5 × age − 161.
  • Harris–Benedict, revised by Roza and Shizgal (1984): men 88.362 + 13.397 × weight + 4.799 × height − 5.677 × age; women 447.593 + 9.247 × weight + 3.098 × height − 4.330 × age.
  • Harris–Benedict, original (1918): men 66.473 + 13.7516 × weight + 5.0033 × height − 6.755 × age; women 655.0955 + 9.5634 × weight + 1.8496 × height − 4.6756 × age.

Worked example

A 30-year-old woman, 165 cm and 60 kg: Mifflin–St Jeor gives 600 + 1,031.25 − 150 − 161 = 1,320 kcal; the revised Harris–Benedict gives 1,384 kcal and the original 1,394 kcal. If she exercises 3 to 5 days a week, her daily needs are about 1,320 × 1.55 = 2,046 kcal.

To turn that into a weight loss or gain target, use the calorie calculator; to split it into protein, carbs and fat, use the macro calculator.

Sources, checked 2 October 2026: Mifflin MD, St Jeor ST et al., Am J Clin Nutr 1990;51(2):241–247; Harris JA, Benedict FG, PNAS 1918;4(12):370–373; Roza AM, Shizgal HM, Am J Clin Nutr 1984;40(1):168–182; Frankenfield D et al., J Am Diet Assoc 2005;105(5):775–789. Estimates for healthy adults, not medical advice.

Frequently asked questions

What is BMR?

Basal metabolic rate is the energy your body uses in a day at complete rest, just to keep you alive: breathing, circulation, temperature and cell repair. It's usually the largest part of the calories you burn each day.

Which BMR formula is the most accurate?

A 2005 systematic review for the American Dietetic Association (Frankenfield and colleagues) found Mifflin–St Jeor the most reliable of the common equations: it came within 10% of measured resting metabolism in more people, both with and without obesity, than the others. Harris–Benedict tends to give a slightly higher figure.

Should I eat my BMR in calories?

No. BMR is what you'd burn lying still all day. You need more than that to cover daily activity: multiply by your activity level (the table under the result) to get your maintenance calories, and don't go below your BMR when dieting without medical advice.

Why does BMR go down with age?

All three equations subtract a little for each year of age, reflecting that older adults tend to have less muscle. Staying active and doing strength training helps keep muscle.

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