BMR Calculator (Basal Metabolic Rate)
Calculate your basal metabolic rate — calories your body burns at complete rest. Mifflin-St Jeor formula.
How it works
Mifflin-St Jeor: men: BMR = 10·weight + 6.25·height − 5·age + 5. women: BMR = 10·weight + 6.25·height − 5·age − 161.
What is BMR?
BMR is the energy your body uses for basic functions while completely at rest — breathing, circulation, cell repair, temperature regulation. It is the floor of your daily caloric need.
BMR vs TDEE — what is the difference?
BMR is the calories used at rest. TDEE (Total Daily Energy Expenditure) is BMR multiplied by an activity factor — your actual daily calorie burn including movement, exercise, and digestion. You eat against TDEE, not BMR. Eating only your BMR while active will create a large deficit.
Why Mifflin-St Jeor?
The Mifflin-St Jeor equation (1990) is the most accurate predictive formula for healthy adults according to multiple validation studies. It replaced the older Harris-Benedict for routine clinical use.
Limitations
Predictive formulas estimate within ±10% of actual BMR for healthy adults. They are less accurate for very lean athletes (often underestimate), very obese individuals, very tall or very short people, and anyone with metabolic disorders. For precision, indirect calorimetry is the gold standard.