BMR Calculator

Your Basal Metabolic Rate (BMR) is the number of calories your body needs to perform basic life-sustaining functions like breathing, circulation, and cell production while completely at rest. BMR typically accounts for 60-75% of your total daily calorie expenditure and is influenced by your age, sex, height, and weight.

Reviewed by GetHealthyCalculators Editorial Team · Updated April 14, 2026

Quick Answer

Average BMR is 1,200–1,600 calories/day for women and 1,400–2,000 for men. BMR is the calories your body burns at complete rest.

These results are estimates based on general formulas and are not a substitute for professional medical advice. Consult a healthcare provider before making health decisions.

Methodology & Sources

Reviewed and updated April 14, 2026 · Prepared by GetHealthyCalculators Editorial Team

This calculator uses the Mifflin-St Jeor equation (Mifflin et al., Am J Clin Nutr 1990;51:241–247), which Frankenfield et al. (J Am Diet Assoc 2005) identified as the most accurate predictive equation compared to indirect calorimetry across non-obese and obese healthy adults (within ±10% of measured REE for roughly 82% of subjects). The Katch-McArdle equation, which uses lean body mass, can be more accurate for very lean or very muscular individuals. BMR estimates are a planning baseline — they cannot replace measured resting metabolic rate via indirect calorimetry for clinical purposes.

References

A new predictive equation for resting energy expenditure in healthy individuals (Mifflin MD et al., Am J Clin Nutr 1990;51:241–247) · American Journal of Clinical Nutrition
Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review (Frankenfield D et al., J Am Diet Assoc 2005;105:775–789) · Journal of the American Dietetic Association
A Biometric Study of Basal Metabolism in Man (Harris JA, Benedict FG, 1919) · Carnegie Institution of Washington
Reassessment of body mass indices (Katch FI, McArdle WD, Am J Clin Nutr 1973) · American Journal of Clinical Nutrition
Daily energy expenditure through the human life course (Pontzer H et al., Science 2021;373:808–812) · Science
Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids · Institute of Medicine / National Academies Press (2005)

How the Formula Works

Measure your weight in kilograms. If using pounds, convert by multiplying by 0.453592.
weight (kg) = weight (lbs) × 0.453592
Measure your height in centimeters. If using feet and inches, convert to centimeters first.
height (cm) = (feet × 12 + inches) × 2.54
Apply the Mifflin-St Jeor equation for males.
BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
Or apply the Mifflin-St Jeor equation for females.
BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161
The result is your estimated BMR in calories per day — the energy your body uses at complete rest.

Limitations

The Mifflin-St Jeor equation estimates BMR and may not reflect your exact metabolic rate, which can only be measured precisely through indirect calorimetry or doubly-labeled water studies.
BMR does not account for individual differences in body composition — two people of the same weight, height, age, and sex may have different BMRs depending on their muscle-to-fat ratio.
Thyroid disorders, certain medications (beta-blockers, stimulants), fever, and pregnancy can significantly alter metabolic rate beyond what the equation predicts.
Extended calorie restriction can cause adaptive thermogenesis, lowering measured BMR 10–15% below predicted values.
Pontzer et al. (Science 2021) showed BMR per unit fat-free mass is relatively stable from age 20 to 60, then declines — so age-adjusted estimates are only approximate.
This tool is designed for generally healthy adults and is not appropriate for children, adolescents, pregnant or breastfeeding women, or anyone with a metabolic disease without clinician oversight.

Frequently Asked Questions

What is BMR and why does it matter?

BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest to maintain basic physiological functions such as breathing, blood circulation, and cell repair. It matters because BMR accounts for the largest portion of your daily calorie expenditure and serves as the foundation for calculating your total calorie needs.

What is the difference between BMR and TDEE?

BMR measures only the calories burned at rest, while TDEE (Total Daily Energy Expenditure) includes BMR plus the calories burned through physical activity, exercise, and the thermic effect of food. TDEE is your BMR multiplied by an activity factor.

How accurate is the Mifflin-St Jeor equation?

The Mifflin-St Jeor equation is considered one of the most accurate predictive formulas for estimating BMR in healthy adults. Research shows it is accurate within about 10% for most people, though individual variation exists due to differences in body composition and genetics.

Can I eat only my BMR calories to lose weight?

Eating at or below your BMR is generally not recommended for sustained periods, as it may not provide enough energy for daily activities and can lead to muscle loss, nutrient deficiencies, and metabolic adaptation. For weight loss, it is safer to eat between your BMR and TDEE.

How can I increase my BMR?

The most effective way to increase your BMR is to build lean muscle mass through resistance training, since muscle tissue burns more calories at rest than fat tissue. Staying well-hydrated, getting adequate sleep, and eating enough protein can also support a healthy metabolic rate.

Does BMR decrease with age?

Yes. BMR tends to decline with age because people often lose lean mass and become less active over time. That decline is one reason calorie needs often fall gradually as adults get older.

Can dieting lower my BMR?

Extended calorie restriction can reduce energy expenditure over time, especially if it causes muscle loss. Preserving lean mass with resistance training and adequate protein helps limit that drop.

Is the Katch-McArdle formula more accurate than Mifflin-St Jeor?

For individuals with unusual body composition (very low or very high body fat), Katch-McArdle — which uses lean body mass — can outperform Mifflin-St Jeor. For the general population, studies like Frankenfield et al. (JADA 2005) find Mifflin-St Jeor the most accurate without needing a body-fat measurement.

Do men and women really have different BMRs at the same weight?

On average yes. Men typically carry more lean mass per kg of body weight, which raises measured BMR. The Mifflin-St Jeor sex-adjustment term (+5 for men, −161 for women) reflects that average difference.

When should I get a clinical BMR measurement?

If you suspect a thyroid disorder, have unexplained weight gain despite low calorie intake, are preparing for metabolic or bariatric surgery, or your calorie targets aren't producing expected results over 6–8 weeks, ask your physician about measured resting metabolic rate (RMR) via indirect calorimetry.

Add your activity level to find your total daily calorie burn

TDEE Calculator

BMR Calculator

Methodology & Sources

References

How the Formula Works

Limitations

Frequently Asked Questions

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