BMR Calculator
Calculate your Basal Metabolic Rate — the calories your body burns at complete rest. Compared across three leading formulas for maximum accuracy.
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What BMR Actually Means?
BMR is the number of calories your body burns doing absolutely nothing — in a temperature-controlled room, lying still, 12+ hours after your last meal. It accounts for approximately 60–75% of total daily energy expenditure for sedentary people. Breathing, heartbeat, brain activity, cell repair, and organ function all consume this energy continuously.
What's the difference between Mifflin-St Jeor and Harris-Benedict?
Mifflin-St Jeor (1990): Male: (10×weight) + (6.25×height) − (5×age) + 5. Female: same minus 161. This is considered the most accurate for most people in studies comparing to measured metabolic rate. Harris-Benedict (revised 1984) tends to overestimate by 5% on average, particularly for sedentary individuals.
What should I know about BMR Is Not TDEE?
BMR is the foundation — to get your Total Daily Energy Expenditure (TDEE), multiply BMR by an activity multiplier (1.2 for sedentary to 1.9 for very active). Eating at BMR level would put most people in a significant deficit. Use the TDEE calculator for your actual calorie needs.
What Affects BMR?
Muscle mass increases BMR — each kilogram of muscle burns approximately 13 kcal/day at rest. Age decreases BMR by roughly 1–2% per decade after 30, partly because of muscle loss. Fasting, very low calorie diets, and extreme weight loss can reduce BMR by 15–40% through adaptive thermogenesis — the metabolic adaptation studied in post-diet 'rebound' research.