BMR Calculator

BMR (Basal Metabolic Rate) is the number of calories your body needs at complete rest to maintain basic life functions: breathing, circulation, cell production, and temperature regulation. It accounts for approximately 60-75% of total daily calorie expenditure for sedentary people.

The Mifflin-St Jeor equation (1990) is generally considered the most accurate for most adults and is recommended by the Academy of Nutrition and Dietetics. The older Harris-Benedict equation (1919, revised 1984) is also widely used. Both formulas are based on height, weight, age, and sex, and typically agree within about 5%.

BMR represents calories burned at rest with zero activity. TDEE (Total Daily Energy Expenditure) multiplies BMR by an activity factor to estimate total daily calories burned, including exercise and daily movement. BMR is the floor; TDEE is the realistic daily calorie requirement.

BMR decreases with age, primarily due to loss of muscle mass (sarcopenia), which burns more calories at rest than fat. Weight loss also reduces BMR since a smaller body requires fewer calories. Strength training helps preserve muscle mass and maintain a higher BMR over time.

Yes. Strength training builds muscle mass, which increases BMR since muscle tissue burns more calories at rest than fat tissue. High-intensity interval training (HIIT) can also create a short-term post-exercise oxygen consumption (EPOC) effect that temporarily elevates metabolic rate. Adequate sleep and avoiding severe caloric restriction also help maintain BMR.