Health
BMR Calculator
Enter your sex, age, height, and weight. We compute your Basal Metabolic Rate using the Mifflin–St Jeor equation, then show what that BMR would mean across the standard activity multipliers.
Sex
Units
BMR is the energy your body would use over 24 hours lying still and not digesting food — your metabolic baseline. To estimate the calories you actually burn in a day, multiply BMR by an activity factor.
For that figure, use the TDEE calculator.
BMR (Mifflin–St Jeor)
1,783 kcal/day
Men · 30y · 82 kg · 178 cm
Estimate, not medical advice. Real BMR varies with body composition, hormones, and health — Mifflin–St Jeor predicts within roughly ±10% for healthy adults.
Examples
30y man, 5′10″, 180 lb
BMR ≈ 1,783 kcal/day
30y woman, 5′6″, 140 lb
BMR ≈ 1,372 kcal/day
45y man, 5′10″, 200 lb
BMR ≈ 1,798 kcal/day
25y woman, 165 cm, 60 kg
BMR ≈ 1,345 kcal/day
How it works
BMR is the calories your body uses over 24 hours at complete rest. Mifflin–St Jeor estimates it from sex, height, weight, and age.
men · 10·kg + 6.25·cm − 5·age + 5
women · 10·kg + 6.25·cm − 5·age − 161
The breakdown also shows what your daily calorie burn would be at each standard activity level (1.2× sedentary through 1.725× very active) — that's the bridge from BMR to TDEE.
Estimate, not medical advice. Mifflin–St Jeor is accurate to about ±10% for healthy adults; real BMR varies with body composition and health. If you have a medical condition, an eating disorder, are pregnant, or have any nutrition concern, talk to a qualified healthcare professional.
Frequently asked questions
Basal Metabolic Rate is the calories your body burns over 24 hours at complete rest — keeping you breathing, circulating blood, regulating temperature, and running basic cell function. It's the metabolic floor before you account for movement, exercise, or digestion.
BMR is the resting baseline. TDEE (Total Daily Energy Expenditure) is BMR multiplied by an activity factor that accounts for movement, exercise, and the thermic effect of food. TDEE is what you'd actually eat to maintain weight; BMR is just the metabolic floor underneath it.
Mifflin–St Jeor — the formula most commonly recommended by registered dietitians. It outperforms the older Harris–Benedict equation in head-to-head accuracy studies. Men: 10·kg + 6.25·cm − 5·age + 5. Women: 10·kg + 6.25·cm − 5·age − 161.
Mifflin–St Jeor predicts BMR within roughly ±10% for healthy adults. Outliers exist — people with very high or very low muscle mass, or with thyroid or other endocrine conditions, can sit further from the prediction. Treat the number as a starting estimate, not a measurement.
On average, men carry more lean mass than women at the same height and weight, and lean tissue is more metabolically active than fat tissue. The Mifflin–St Jeor offset (+5 for men, −161 for women) approximates this difference at the population level. Individual variation is large — the formula is a population estimator.
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