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BMR Calculator

Find your basal metabolic rate, the calories your body burns at rest, plus your daily calorie needs by activity level.

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BMR Calculator Nothing is stored or sent

For general information only, not medical advice. Results are estimates and do not replace a check-up with a doctor or other qualified health professional.

What your result means

Your BMR is the energy your body needs just to stay alive at rest: breathing, pumping blood, keeping warm and running your brain and organs. It does not include walking, exercise or digesting food. To find how much you burn in a full day, the calculator multiplies your BMR by an activity factor.

Activity level Description Daily calories
Sedentary Little or no exercise BMR × 1.2
Lightly active Exercise 1 to 3 days a week BMR × 1.375
Moderately active Exercise 3 to 5 days a week BMR × 1.55
Very active Exercise 6 to 7 days a week BMR × 1.725
Extra active Hard daily exercise or a physical job BMR × 1.9

The calculator fills in this table with your own numbers. The sedentary row is the least you burn on a normal day. Your BMR on its own is lower still, because nobody spends the whole day lying still.

How BMR is calculated

The headline result uses the Mifflin-St Jeor equation, published in 1990:

  • Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) + 5
  • Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age (years) − 161

Each extra kilogram adds 10 kcal and each extra centimetre adds 6.25 kcal. Each year of age takes off 5 kcal. The final number adjusts for sex, because men usually have more muscle.

For comparison, the calculator also shows the revised Harris-Benedict equation (Roza and Shizgal, 1984):

  • Men: BMR = 88.362 + 13.397 × weight (kg) + 4.799 × height (cm) − 5.677 × age (years)
  • Women: BMR = 447.593 + 9.247 × weight (kg) + 3.098 × height (cm) − 4.330 × age (years)

Harris-Benedict usually gives a slightly higher number. If you use imperial units, the calculator converts feet, inches and pounds to centimetres and kilograms first. All results are rounded to the nearest whole calorie.

How to use the BMR calculator

  1. Choose Metric or Imperial and select your sex.
  2. Enter your age (18 to 80).
  3. Enter your height and weight.
  4. Read your Mifflin-St Jeor BMR, the Harris-Benedict figure, and the table of daily calories by activity level. Results update as you type.

Worked example

Arjun is a 30-year-old man. He is 172 cm tall (about 5 ft 8 in) and weighs 75 kg (about 165 lb).

Mifflin-St Jeor: 10 × 75 + 6.25 × 172 − 5 × 30 + 5 = 750 + 1,075 − 150 + 5 = 1,680 kcal.

Harris-Benedict: 88.362 + 13.397 × 75 + 4.799 × 172 − 5.677 × 30 = 88.362 + 1,004.775 + 825.428 − 170.31 = 1,748.255, shown as 1,748 kcal. That is 68 kcal higher than Mifflin-St Jeor.

His daily calories by activity level, using 1,680 kcal:

  • Sedentary: 1,680 × 1.2 = 2,016 kcal
  • Lightly active: 1,680 × 1.375 = 2,310 kcal
  • Moderately active: 1,680 × 1.55 = 2,604 kcal
  • Very active: 1,680 × 1.725 = 2,898 kcal
  • Extra active: 1,680 × 1.9 = 3,192 kcal

If Arjun has a desk job and walks a little, about 2,000 kcal a day keeps his weight steady. To plan weight loss from there, use the calorie calculator.

Which BMR formula is most accurate?

A 2005 systematic review in the Journal of the American Dietetic Association (Frankenfield and colleagues) compared the most common equations: Harris-Benedict, Mifflin-St Jeor, Owen and WHO/FAO/UNU. Mifflin-St Jeor was the most reliable. It predicted resting burn within 10% of the measured value in more people than any other equation, both in people with and without obesity, and it had the narrowest error range.

The same review noted that older adults and ethnic minorities were poorly represented in the studies. So for Indians and other South Asians, treat any equation as a rough guide. The only way to measure BMR exactly is indirect calorimetry, a breathing test done in some clinics and labs.

BMR in Indians

Indian data suggest the usual equations can run high for Indian bodies. When the ICMR-National Institute of Nutrition revised India’s energy requirements in 2020, it found that the international FAO/WHO/UNU equations overestimate the BMR of Indians by 10% to 12%. Its explanation: those equations were built largely on young, muscular people, while Indians tend to carry relatively more fat at the same weight. ICMR-NIN now reduces predicted BMR by 10% for Indian adults (ICMR-NIN, 2020 (opens in new tab)).

That finding is about the FAO/WHO/UNU equations. ICMR-NIN did not assess Mifflin-St Jeor, and the 2005 review found little validation work in ethnic minorities. The practical takeaway is the same: use your result as a starting estimate that may be on the high side. If your weight does not move as expected after two to three weeks of steady eating, trust the scale over the formula and adjust by 100 to 200 kcal.

What is a normal BMR?

There is no single normal BMR. It depends on body size, age, sex and muscle. These Mifflin-St Jeor examples show typical values:

Person Height Weight BMR
Woman, 25 156 cm 55 kg 1,239 kcal
Woman, 30 160 cm 65 kg 1,339 kcal
Woman, 45 156 cm 60 kg 1,189 kcal
Man, 25 168 cm 65 kg 1,580 kcal
Man, 30 176 cm 80 kg 1,755 kcal
Man, 45 168 cm 72 kg 1,550 kcal

A calculator cannot detect a slow metabolism. If you feel very tired, feel cold more than usual and are putting on weight without a clear reason, see a doctor: these are common symptoms of an underactive thyroid (opens in new tab), which a simple blood test can check.

How to use your BMR number

BMR is a building block, not a diet target. Start from your BMR, multiply it by your activity factor to get your daily burn (TDEE), then set your food intake from there. Eating about 500 kcal below TDEE leads to a loss of roughly 0.5 kg a week for most people. For many adults, that target still sits above BMR, which is a good sign the plan is not too harsh. If your target falls below your BMR, the deficit is probably too large.

Limitations

BMR equations estimate an average for people of your size, age and sex. Your real BMR can be higher or lower.

  • Body composition: the formulas do not know how much of your weight is muscle. Muscular people often burn more than predicted.
  • Obesity: extra weight is partly fat, which burns less energy than muscle, so the result may be too high.
  • Health conditions: thyroid disease, fever, recent illness, some medicines and long-term dieting can all change BMR.
  • Not for: pregnancy, breastfeeding, under-18s, or people in hospital, who need a clinician’s assessment.

Use BMR as a planning number, then adjust based on how your weight changes over a few weeks. See a doctor or dietitian if you plan a large calorie cut or have a medical condition.

Key facts

FAQ

BMR Calculator FAQs

What is BMR?

BMR, or basal metabolic rate, is the number of calories your body burns at complete rest to keep you alive. It covers breathing, blood circulation, body temperature, and brain and organ function. For most people, BMR is the largest part of their daily calorie burn. It depends mainly on your weight, height, age, sex and muscle mass.

What is the difference between BMR and TDEE?

BMR is what you burn at complete rest, while TDEE (total daily energy expenditure) is everything you burn in a day. TDEE adds the energy used for digestion, daily movement and exercise on top of BMR. The calculator estimates TDEE by multiplying BMR by an activity factor from 1.2 (sedentary) to 1.9 (extra active).

Which BMR formula is the most accurate?

The Mifflin-St Jeor equation is the most accurate of the common BMR formulas for healthy adults. A 2005 systematic review found it predicted resting burn within 10% of the measured value in more people than Harris-Benedict, Owen or WHO/FAO/UNU. It still has errors for individuals, especially very muscular people and groups that were under-studied.

What is a normal BMR?

There is no single normal BMR, because it depends on your size, age, sex and muscle. By the Mifflin-St Jeor equation, a 30-year-old woman of 160 cm and 65 kg has a BMR of about 1,339 kcal. A 30-year-old man of 176 cm and 80 kg has about 1,755 kcal. Enter your details to see your own figure.

Is BMR lower for Indians?

Indian studies suggest it often is, for the same body weight. ICMR-NIN found the international FAO/WHO/UNU equations overestimate the BMR of Indian adults by 10% to 12%, likely because Indians carry relatively more fat and less muscle at the same weight. So treat any calculator result as a starting estimate and adjust it based on how your weight actually changes.

Does BMR decrease with age?

Yes, BMR tends to fall with age, and the Mifflin-St Jeor formula takes off 5 kcal per year. A large 2021 study in Science found that, adjusted for body size, energy use stays fairly stable from 20 to 60 and declines after 60. Much of the earlier drop people notice comes from losing muscle and moving less.

How can I increase my BMR?

The most reliable way to raise your BMR is to build muscle with regular strength training. In the 1990 Mifflin study, fat-free mass was the best single predictor of resting energy use. Eating enough protein and avoiding very low calorie diets help you keep the muscle you have. Moving more raises your total burn (TDEE), though not BMR itself.

Is it safe to eat below my BMR?

Eating below your BMR is not advised for most people without medical supervision. Your BMR covers your basic body functions, so eating less makes it hard to get enough nutrients and can lead to muscle loss and tiredness. A safer plan is to eat around 500 kcal below your TDEE, which is usually still above your BMR.