Calculate your Basal Metabolic Rate using the most accurate formulas — Mifflin-St Jeor, Harris-Benedict, and Katch-McArdle. Understand the difference between BMR and TDEE and how to use it for your goals.
Average values by gender, Mifflin-St Jeor formula
Use our full calorie calculator to compute your BMR and TDEE based on your exact measurements and activity level.
Open Calorie CalculatorBasal Metabolic Rate (BMR) is the minimum number of calories your body requires to sustain basic physiological functions at complete rest — no movement, no digestion, just the energy cost of staying alive. This includes breathing, heartbeat, maintaining body temperature, cell production, and organ function. For most people, BMR accounts for 60–75% of total daily calorie expenditure, making it the single largest component of your energy budget.
Understanding your BMR is the starting point for any calorie-based nutrition plan. Whether your goal is weight loss, muscle gain, or athletic performance, your BMR provides the metabolic baseline from which all calculations flow.
1. Mifflin-St Jeor (1990) — Most Recommended:
Women: BMR = 10×weight(kg) + 6.25×height(cm) − 5×age − 161
Men: BMR = 10×weight(kg) + 6.25×height(cm) − 5×age + 5
Most validated formula across diverse populations; preferred by registered dietitians.
2. Harris-Benedict (Revised 1984):
Women: BMR = 447.593 + 9.247×weight(kg) + 3.098×height(cm) − 4.330×age
Men: BMR = 88.362 + 13.397×weight(kg) + 4.799×height(cm) − 5.677×age
Long-established formula; slightly less accurate than Mifflin-St Jeor for most people.
3. Katch-McArdle (Uses Lean Body Mass):
BMR = 370 + 21.6 × Lean Body Mass(kg)
Requires knowing your body fat percentage. Most accurate for lean, athletic individuals as it directly accounts for metabolically active muscle mass.
BMR is your calorie burn at rest. TDEE (Total Daily Energy Expenditure) is your actual calorie burn across the full day including all physical activity. TDEE is calculated by multiplying BMR by an activity factor:
• Sedentary (little/no exercise): BMR × 1.2
• Lightly active (1–3 days/week exercise): BMR × 1.375
• Moderately active (3–5 days/week): BMR × 1.55
• Very active (6–7 days/week hard exercise): BMR × 1.725
• Extra active (physical job + daily exercise): BMR × 1.9
Your TDEE is the calorie level at which your weight stays stable. To lose weight, eat below TDEE; to gain muscle, eat above it. Use our calorie calculator to compute your TDEE instantly.
Several factors influence BMR beyond just body size: Muscle mass — muscle burns ~6 cal/lb/day at rest vs ~2 cal/lb for fat, so more muscle means higher BMR. Age — BMR decreases approximately 2–3% per decade after age 20 due to muscle loss. Sex — men average 5–15% higher BMR than women of the same size due to greater muscle mass and testosterone. Hormones — thyroid hormones, cortisol, and insulin significantly influence metabolic rate. Genetics — some individuals have naturally higher or lower BMRs than formulas predict.
Never eat below your BMR for extended periods — this is a common mistake. Your BMR represents the minimum calories needed to keep organs functioning; going below this triggers metabolic adaptation, muscle loss, and hormonal disruption. Instead, calculate your TDEE and create a deficit of 500–750 calories from that number. This ensures you lose primarily fat while preserving muscle and keeping your metabolism healthy. Use our calorie calculator to set the right target for your goals.
BMR varies widely by individual. The average woman's BMR is approximately 1,400 calories/day; the average man's is approximately 1,800 calories/day. Athletes and very muscular individuals may have BMRs significantly above average, while sedentary individuals with low muscle mass may be below average.
Yes — the most effective way to raise BMR is to build lean muscle mass through resistance training. Each pound of muscle burns approximately 3× more calories at rest than a pound of fat. Eating adequate protein, staying hydrated, and avoiding prolonged severe caloric restriction also help preserve a healthy metabolic rate.
Use Mifflin-St Jeor for most people — it's the most accurate validated formula that only requires age, sex, height, and weight. If you know your body fat percentage, Katch-McArdle may be more precise, especially if you're athletic or have an unusual body composition.
BMR naturally declines with age — approximately 2–3% per decade after age 20. A 50-year-old typically has a BMR 6–9% lower than at age 20, primarily due to muscle mass loss (sarcopenia). Regular resistance training is the most effective strategy to counteract age-related metabolic decline.