BMR Calculator (Basal Metabolic Rate)
Calculate your Basal Metabolic Rate using Mifflin-St Jeor, Harris-Benedict, and Katch-McArdle formulas.
Your Basal Metabolic Rate (BMR) is the number of calories your body needs to perform basic life-sustaining functions like breathing, circulation, cell production, and temperature regulation. It represents the minimum energy your body uses while at complete rest.
This calculator provides results from three established formulas. The Mifflin-St Jeor equation (1990) is considered the most accurate for most people and is recommended by the Academy of Nutrition and Dietetics. The Harris-Benedict equation (1919, revised 1984) is the oldest and most widely known. The Katch-McArdle formula accounts for lean body mass but requires knowing your body fat percentage.
BMR accounts for roughly 60-75% of your total daily calorie expenditure. The remaining calories are burned through physical activity (15-30%) and the thermic effect of food (around 10%). Factors that influence BMR include age, gender, weight, height, genetics, and body composition.
BMR naturally decreases with age — roughly 1-2% per decade after age 20. Maintaining muscle mass through resistance training helps keep your BMR higher as you age.