The BMR calculator computes your Basal Metabolic Rate — the number of calories your body needs at complete rest just to maintain vital functions — and your Total Daily Energy Expenditure (TDEE) based on your activity level. These two numbers are the foundation of any nutrition and weight management plan.
BMR is calculated using the Mifflin-St Jeor equation, the most accurate formula for most adults. TDEE multiplies your BMR by an activity factor ranging from 1.2 (sedentary) to 1.9 (very active). The result tells you exactly how many calories you burn each day.
Your BMR accounts for 60–70% of total daily calorie expenditure. Even during sleep, your body burns calories to maintain breathing, circulation, body temperature, and cellular repair.
Use this calculator as a starting point for any health or fitness goal that requires a numeric benchmark. The result is an estimate, not a diagnosis — but it provides a concrete figure to track against over time.
The most common mistake is treating the result as a precise measurement rather than an evidence-based estimate. All body metric calculators have margins of error — use the result as a tracking baseline, not a clinical diagnosis.
A personal trainer uses the calculator with a new client to set a measurable starting point. Re-running the calculation at 4-week intervals provides an objective progress metric that supports motivation and programme adjustments.
Mifflin-St Jeor BMR Formula
Men: BMR = (10 × kg) + (6.25 × cm) − (5 × age) + 5
Women: BMR = (10 × kg) + (6.25 × cm) − (5 × age) − 161
TDEE = BMR × Activity Factor
Activity factors: Sedentary 1.2, Light 1.375, Moderate 1.55, Active 1.725, Very Active 1.9.
A 28-year-old man, 180 cm, 80 kg, moderately active.
Result: BMR = 1,790 kcal | TDEE = 2,775 kcal/day. To lose 1 lb/week, eat ~2,275 kcal.
Basal Metabolic Rate is the minimum calories your body needs at complete rest (no physical activity). It represents the energy required for breathing, circulation, organ function, and cellular maintenance.
BMR is your resting calorie burn. TDEE (Total Daily Energy Expenditure) adds the calories burned through physical activity. For weight management, TDEE is the more useful number.
Strength training builds muscle mass, which increases BMR (muscle burns more calories at rest than fat). Eating enough protein also helps prevent metabolic adaptation during weight loss.
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