BMR
Basal metabolic rate.
What does BMR mean?
Basal Metabolic Rate (BMR) is the number of calories your body needs to perform basic life-sustaining functions — breathing, circulation, cell production, and nutrient processing — while completely at rest. It represents the largest component of your total daily energy expenditure (about 60–75%) and is the foundation for calculating how many calories you need each day.
How to calculate BMR
This calculator uses the Mifflin-St Jeor equation, which is considered the most accurate for most adults. For men: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5. For women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161. To estimate total daily calorie needs, multiply your BMR by an activity factor: sedentary (×1.2), lightly active (×1.375), moderately active (×1.55), very active (×1.725), or extra active (×1.9).
FAQ
BMR is the calories burned at complete rest. TDEE (Total Daily Energy Expenditure) includes BMR plus all additional activity — exercise, walking, digestion, and non-exercise movement. TDEE is your actual daily calorie burn and is calculated by multiplying BMR by an activity factor.
As you age, you naturally lose muscle mass (sarcopenia) and hormonal changes slow metabolism. After age 20, BMR decreases by roughly 1–2% per decade. Strength training can help preserve muscle mass and maintain a higher BMR.
Men typically have more lean muscle mass and less body fat than women of the same weight, and muscle tissue burns more calories at rest than fat tissue. This is why the Mifflin-St Jeor equation applies a different constant (+5 for men, −161 for women).
Studies show the Mifflin-St Jeor equation predicts BMR within 10% for most healthy adults, making it more accurate than the older Harris-Benedict equation. However, individual variation exists — factors like body composition, genetics, and thyroid function can cause your actual BMR to differ.
Yes. First calculate your TDEE (BMR × activity factor). To lose weight, eat fewer calories than your TDEE (a 500 cal/day deficit results in roughly 1 lb/week loss). To gain weight, eat above your TDEE. Never eat below your BMR, as this can slow metabolism and cause nutrient deficiencies.
Related calculators
- BMI— Body mass index estimate.
- Calorie Needs (TDEE)— Total daily energy expenditure.
- Body Fat %— Estimated fat proportion.
- Heart Rate Zone— Target exercise range.