Enter age, gender, height, weight, and activity level to see maintenance calories (TDEE) plus suggested calories for fat loss, recomposition, or lean mass gain.
Understanding the simple steps to calculate your Basal Metabolic Rate accurately
Input age, gender, height, weight, and activity.
We use Mifflin-St Jeor as the standard formula.
Get TDEE (your daily maintenance calories).
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Track precise age.
Convert between units.
See weight category by WHO standards.
Estimate % of body fat and lean mass.
Daily calories for loss, maintenance, or gain.
Total daily energy expenditure by activity.
Basal Metabolic Rate is the minimum energy needed to sustain life at complete rest—fueling your heart, brain, lungs, and cells. It accounts for 60–75% of daily calorie use.
Metabolism slows ~1–2% per decade after your 20s.
Some people naturally burn more calories due to inherited traits.
Cold raises BMR as the body heats itself. Very hot conditions can also raise it as the body works to cool down.
Severe restriction lowers BMR (similar to power-saving mode). Frequent, balanced meals can help maintain it.
Carrying a fetus increases BMR. Menopause and hormonal shifts may raise or lower it.
Caffeine and certain medications temporarily raise metabolic rate.
Increases lean mass, raising resting burn.
Higher thermic effect of digestion.
Creates lasting afterburn.
Hormones that regulate hunger and energy improve with 7–9 hours.
BMR is measured under the strictest conditions, while RMR (resting metabolic rate) is measured in a relaxed state but not fully inactive. RMR is usually 10–20% higher than BMR. Many people use the terms interchangeably, but technically they differ.
While online calculators provide good estimates, the most accurate way to measure BMR is through calorimetry devices, available in some fitness centers, medical clinics, or research labs. These tests measure oxygen consumption to estimate energy expenditure.
Even with precise formulas, studies show there’s still a ~25% variance between individuals due to genetics, hormones, and lifestyle factors. That’s why BMR and TDEE results should be treated as estimates, not absolutes. The best approach is to track progress with food logs, body weight, and energy levels, then adjust intake and activity over time.
Get answers to common questions about BMR and metabolic rate calculations
BMR is measured under strict conditions (fasting, rest, controlled temperature). RMR (resting metabolic rate) is measured in less strict conditions and is usually 10–20% higher.
We use the Mifflin-St Jeor equation, considered most accurate for healthy adults. Results are estimates—factors like thyroid health, muscle mass, and genetics can shift actual needs.
Yes. BMR helps set your baseline. By applying an activity factor, you get TDEE. Then create a safe deficit (−500 to −1000/day) for steady weight loss.
Our calculator uses Mifflin-St Jeor as the default, but we also explain Harris-Benedict and Katch-McArdle for advanced cases.
No. Eating below BMR for extended time can slow metabolism, reduce muscle, and risk nutrient deficiencies. Base weight-loss plans on TDEE, not below-BMR intakes.
Primarily due to muscle loss and hormonal changes. Resistance training and higher protein intake help maintain metabolism.
Yes. Men usually have higher lean mass, which raises their BMR. Formulas adjust for sex differences.
Recalculate every 10–15 lbs lost or gained, or if activity changes significantly. For maintenance, check every 3–6 months.
Yes—muscle gain, regular workouts, protein intake, sleep, hydration, and stress management all help.