BMR Calculator
Calculate your Basal Metabolic Rate — the calories your body burns at complete rest.
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Select your sex
How This Calculator Works
Mifflin-St Jeor (1990)
The most widely recommended formula, validated by the Academy of Nutrition and Dietetics as the most accurate predictor of BMR for both normal weight and obese individuals.
Men: BMR = (10 × weightkg) + (6.25 × heightcm) − (5 × age) + 5
Women: BMR = (10 × weightkg) + (6.25 × heightcm) − (5 × age) − 161
Harris-Benedict Revised (1984)
The original 1919 equation revised by Roza and Shizgal. Still widely used but tends to slightly overestimate compared to Mifflin-St Jeor.
Men: BMR = 88.362 + (13.397 × weightkg) + (4.799 × heightcm) − (5.677 × age)
Women: BMR = 447.593 + (9.247 × weightkg) + (3.098 × heightcm) − (4.330 × age)
Katch-McArdle (1977)
Uses lean body mass rather than total weight, making it the most accurate choice when body fat percentage is known. Particularly useful for athletic or very lean individuals.
BMR = 370 + (21.6 × lean masskg)
Where lean mass = weight × (1 − body fat % / 100)
Frequently Asked Questions
What is BMR and how is it different from TDEE?
BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest to maintain basic life functions like breathing, circulation, and cell repair. TDEE (Total Daily Energy Expenditure) includes your BMR plus all additional calories burned through daily activities, exercise, and digestion (the thermic effect of food). Your BMR typically accounts for 60-75% of your TDEE.
Which BMR formula is most accurate?
The Mifflin-St Jeor equation (1990) is considered the most accurate for the general population. A 2005 review by Frankenfield et al. in the Journal of the American Dietetic Association found it predicted BMR within 10% of measured values for the majority of subjects. If you know your body fat percentage, the Katch-McArdle formula may be more accurate, especially for athletic or very lean individuals.
Why do men and women have different BMR values?
Men generally have a higher BMR than women due to greater average muscle mass and lower average body fat percentage. Muscle tissue is metabolically more active than fat tissue, burning approximately 6 calories per pound per day compared to about 2 calories per pound for fat. The Mifflin-St Jeor equation accounts for this with different constants for each sex.
Can I increase my BMR?
Yes. The most effective way to increase BMR is to build lean muscle mass through resistance training. Research in the European Journal of Clinical Nutrition (2015) found that 10 weeks of resistance training increased resting metabolic rate by approximately 7%. Other factors that influence BMR include adequate sleep, sufficient protein intake, and avoiding extreme calorie restriction, which can lower BMR by 15-20%.
Should I eat below my BMR to lose weight?
Eating below your BMR is generally not recommended. Sustained calorie intake below BMR can lead to muscle loss, metabolic adaptation, nutrient deficiencies, and hormonal disruption. For safe weight loss, aim for a moderate deficit of 300-500 calories below your TDEE (not BMR). The American College of Sports Medicine recommends women consume at least 1,200 calories/day and men at least 1,500 calories/day.
How does age affect my BMR?
BMR decreases by approximately 1-2% per decade after age 20, primarily due to the gradual loss of muscle mass (sarcopenia). A study in the American Journal of Clinical Nutrition found that BMR declines by about 150 calories per decade. Regular resistance training and adequate protein intake (1.2-1.6 g/kg/day) can help slow this decline by maintaining lean muscle mass.
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