BMR Calculator
Estimate your Basal Metabolic Rate — the calories your body burns at rest — using the Mifflin-St Jeor equation.
Enter your body fat percentage to also calculate BMR with the Katch-McArdle formula.
Your BMR
Mifflin-St Jeor (recommended)
Energy Equivalent
Kilojoules per day
Formula Comparison
| Formula | kcal/day | kJ/day |
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Your BMR is the number of calories your body burns at complete rest. To estimate your total daily calorie needs (with activity), use the TDEE Calculator.
What Is Basal Metabolic Rate (BMR)?
Your Basal Metabolic Rate (BMR) is the number of calories your body needs to keep functioning while at complete rest. It represents the energy spent on essential, involuntary processes that keep you alive: breathing, circulating blood, regulating body temperature, growing and repairing cells, and basic brain and nerve function. BMR is measured in a fasted, rested, thermally neutral state and typically accounts for 60-70% of the total calories an average person burns each day.
BMR is influenced by several factors. Muscle (lean) mass is metabolically active and raises BMR, which is why two people of the same weight can have different metabolic rates. Men generally have a higher BMR than women due to greater lean mass, and BMR tends to decline with age as muscle mass decreases. Knowing your BMR is the starting point for managing weight, planning nutrition, and setting realistic calorie targets.
BMR vs. TDEE: What's the Difference?
BMR is only the energy you burn at rest. Your Total Daily Energy Expenditure (TDEE) is the total number of calories you burn in a full day, including everyday activity, exercise, and the energy used to digest food (the thermic effect of food). TDEE is calculated by multiplying your BMR by an activity factor that reflects how active you are.
In short: BMR is what you would burn if you stayed in bed all day, while TDEE is what you actually burn living your life. For weight loss or weight gain goals, you compare your calorie intake to your TDEE, not your BMR. To calculate yours, visit the TDEE Calculator.
BMR Formulas Explained
Mifflin-St Jeor Equation (Recommended)
Introduced in 1990, the Mifflin-St Jeor equation is considered the most accurate BMR formula for the general modern population and is widely recommended by dietitians. It uses weight, height, age, and sex.
Men: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
Women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161
Revised Harris-Benedict Equation
The original Harris-Benedict equation dates to 1919 and was revised by Roza and Shizgal in 1984. It also uses weight, height, age, and sex, and tends to give slightly higher estimates than Mifflin-St Jeor.
Men: BMR = 13.397 × weight(kg) + 4.799 × height(cm) − 5.677 × age + 88.362
Women: BMR = 9.247 × weight(kg) + 3.098 × height(cm) − 4.330 × age + 447.593
Katch-McArdle Formula (Requires Body Fat %)
The Katch-McArdle formula is based on lean body mass (LBM) rather than total weight, making it more accurate for lean and athletic individuals. It only applies when you know your body fat percentage.
LBM = weight(kg) × (1 − body fat % / 100)
BMR = 370 + 21.6 × LBM