BMR Calculator

BMR (Basal Metabolic Rate) represents the bare minimum number of calories your body needs to maintain basic life-sustaining functions — such as breathing, circulation, cell production, and nutrient processing — while at complete rest in a temperate environment. In contrast, TDEE (Total Daily Energy Expenditure) is the total calories you burn in a day once you add physical activity, workouts, walking, and the energy required to digest food (TEF). BMR is always lower than TDEE.

For most non-obese, healthy adults, BMR formulas like Mifflin-St Jeor are highly accurate, yielding estimations within ±10% of values measured in laboratory clinical settings. However, BMR is influenced by body composition; individuals with higher muscle mass will burn more calories at rest than predicted, while those with higher body fat percentages may burn slightly less. For elite athletes, a formula that includes body fat percentage (like Katch-McArdle) is more precise.

It is highly discouraged to consume fewer calories than your BMR. Doing so places your body in a severe energy deficit that can lead to muscle loss, nutrient deficiencies, fatigue, hormonal imbalances, and a drop in overall metabolic rate (known as adaptive thermogenesis). For safe and sustainable weight loss, it is recommended to eat in a moderate deficit relative to your TDEE (typically TDEE − 300 to 500 calories), while remaining at or above your BMR.

BMR typically decreases by approximately 1–2% per decade after the age of 20. This decline is largely caused by the natural, gradual loss of lean muscle mass (sarcopenia) that occurs as people age, rather than a permanent cellular slowdown. Regular resistance training and adequate protein intake can significantly slow, halt, or even reverse this age-related metabolic decline.

Yes, men generally have a BMR that is 5–10% higher than women of the same height and weight. This difference is primarily due to body composition: men typically carry a higher percentage of lean skeletal muscle, which is metabolically active tissue, whereas women naturally carry a higher percentage of body fat to support reproductive and endocrine functions.

Yes. Muscle tissue is metabolically active, burning approximately 10 to 13 calories per kilogram (4.5 to 6 kcal/lb) per day at complete rest. Fat tissue, on the other hand, is mostly storage and burns only about 4 to 5 calories per kilogram (2 kcal/lb) per day. By building lean muscle through weight training, you can permanently increase your resting metabolic rate.

The single most effective way to permanently increase your BMR is by increasing your lean muscle mass through regular resistance training (such as lifting weights or bodyweight training). Additionally, consuming sufficient protein supports muscle synthesis and recovery. In the short term, getting adequate sleep, staying hydrated, and avoiding extreme low-calorie diets prevent BMR from dropping below normal.

The Mifflin-St Jeor equation is a mathematical formula published in 1990 that predicts basal metabolic rate. It is widely considered by medical and nutritional organizations (including the Academy of Nutrition and Dietetics) to be the most accurate BMR formula for the general population. It uses weight, height, age, and biological sex as its primary variables.