BMR Calculator

BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest just to keep basic functions running — breathing, circulation, cell production. It's typically 60–75% of your total daily calorie burn. Knowing your BMR tells you the absolute minimum calories your body needs to survive, and is the starting point for calculating how much to eat to lose, maintain, or gain weight.

We use the Mifflin-St Jeor equation, which is considered the gold standard by US dietitians and the Academy of Nutrition and Dietetics. For men: BMR = (10 × kg) + (6.25 × cm) − (5 × age) + 5. For women: BMR = (10 × kg) + (6.25 × cm) − (5 × age) − 161. This formula is more accurate than the older Harris-Benedict equation, especially for people with higher body weights.

Average BMR for American adult women ranges from 1,400–1,600 calories/day; for men, 1,700–2,000/day. These figures vary based on height, weight, age, and muscle mass. Taller, heavier, younger, and more muscular individuals have higher BMRs. Age gradually reduces BMR as muscle mass decreases — typically by 1–2% per decade after age 30.

BMR is how many calories you burn at absolute rest. TDEE (Total Daily Energy Expenditure) is BMR multiplied by an activity factor to account for exercise and daily movement. If your BMR is 1,500 calories and you exercise moderately 3x/week, your TDEE might be ~2,070 calories — that's your daily maintenance level. Use our Calorie Calculator to see your full TDEE.

Yes — the most effective way to raise BMR is to build muscle through strength training. Muscle burns more calories at rest than fat tissue. Adequate protein intake (0.7–1g per pound of body weight) supports muscle retention. Staying hydrated, sleeping 7–9 hours nightly, and avoiding severe calorie restriction also help prevent BMR from dropping (metabolic adaptation).

Significantly — BMR typically decreases by roughly 1–2% per decade after age 30 due to natural muscle loss (sarcopenia) and hormonal changes. A 50-year-old woman may have a BMR 150–200 calories lower than the same woman at 30. This is why many Americans find weight management harder in middle age even without changing their eating habits.

Predictive equations like Mifflin-St Jeor estimate BMR within ±10% for most people. The only way to measure BMR precisely is through indirect calorimetry in a clinical setting. For practical diet planning, these estimates are sufficiently accurate. If you have a medical condition affecting metabolism (thyroid disorders, diabetes), consult your physician for personalized caloric guidance.

Once you know your BMR, multiply by your activity level (sedentary = ×1.2, lightly active = ×1.375, moderately active = ×1.55, very active = ×1.725) to get your TDEE. To lose weight, eat 300–500 calories below TDEE. Never eat below your BMR regularly — doing so signals your body to slow metabolism further and can cause nutrient deficiencies.