Calculated using standard mathematical and industry formulas.
Basal Metabolic Rate (BMR) measures the baseline number of calories your body burns at complete rest to maintain vital functions like breathing, heart rate, and cell production. Calculated using the Mifflin-St Jeor equation, BMR accounts for 60% to 75% of your total daily calorie burn.
How to use this calculator?
Select your unit system (metric or imperial), biological sex, age, height, and weight.
Optionally enter your body fat percentage if known.
Compare your resting energy expenditure across Mifflin-St Jeor, Harris-Benedict, and Katch-McArdle equations.
Use your BMR baseline to establish daily calorie minimums or calculate TDEE.
BMR Men = (10 × Weight kg) + (6.25 × Height cm) - (5 × Age) + 5; BMR Women = (10 × Weight kg) + (6.25 × Height cm) - (5 × Age) - 161
W = weight in kg, H = height in cm, A = age in years, LBM = Lean Body Mass in kg = W × (1 − BodyFat%).
Step-by-step calculation example
Male 30y, 175cm, 70kg, 18% body fat → Mifflin: 1,649 kcal/day, Harris-Benedict: 1,695 kcal/day, Katch-McArdle: 1,610 kcal/day.
Key insights to remember
BMR accounts for approximately 60–75% of a sedentary person's total daily energy expenditure.
Mifflin-St Jeor is the primary clinical benchmark because it provides the highest statistical accuracy for modern populations.
Muscle tissue is more metabolically active than fat tissue, burning ~13 kcal/kg/day at rest compared to ~4.5 kcal/kg/day for fat.
BMR naturally declines by 1–2% per decade after age 30, primarily due to age-related loss of lean muscle mass (sarcopenia).
Prolonged severe calorie restriction (crash dieting) can lower BMR through adaptive thermogenesis (metabolic adaptation).
How to interpret your results?
Basal Energy Needs
Your BMR represents the baseline calories burned at complete rest to maintain vital involuntary functions like breathing, heart rate, and cellular repair.
Expert advice & guidance
💡 Nutrition tip: Never restrict daily calorie intake below your calculated BMR without professional medical supervision, as severe deficits trigger metabolic slowdown and muscle loss.
Frequently asked questions
What is Basal Metabolic Rate (BMR) and how is it calculated?
BMR is the daily calories your body burns at complete rest for basic physiological functions. It is calculated using the Mifflin-St Jeor formula based on weight, height, age, and sex.
What is the difference between BMR and TDEE?
BMR measures baseline calories burned doing nothing in bed. TDEE (Total Daily Energy Expenditure) combines BMR with your daily physical activity and exercise level.
How can I safely increase my Basal Metabolic Rate (BMR)?
Increase BMR by building lean muscle mass through resistance training, optimizing sleep, staying hydrated, and consuming adequate dietary protein.
Why does BMR decrease with age?
BMR naturally slows with age due to gradual loss of muscle tissue (sarcopenia) and age-related metabolic and hormonal shifts.
Related calculators
TDEE Calculator: Total Daily Energy Calories — Calculate your Total Daily Energy Expenditure (TDEE) based on your activity level. Find exact calories for weight loss, maintenance, or muscle gain.
Calorie Calculator: Daily Maintenance & Loss — Calculate daily calories for weight loss, maintenance, or muscle gain. Uses Mifflin-St Jeor and Harris-Benedict formulas to set safe, healthy calorie targets.
Body Fat Calculator: Tape Measure Navy Method — Calculate your body fat percentage, lean body mass, and fat mass using the US Navy circumference method. Track fitness body recomposition and waist measurements.