Calculate your Basal Metabolic Rate — the calories your body burns at complete rest — using three validated formulas side by side.
Quick summary: BMR (Basal Metabolic Rate) is the energy your body needs just to stay alive at complete rest — breathing, circulation, cell repair, brain function. It typically accounts for 60–75% of total daily calories burned. Multiply BMR by an activity factor to get TDEE, the number to actually plan a diet around.
Basal Metabolic Rate is the minimum number of calories your body needs over 24 hours to keep essential functions running while lying still, awake, and fasted — it does not include digestion, movement, or exercise. It is closely related to (and often used loosely interchangeably with) Resting Metabolic Rate (RMR), which is measured under slightly less strict lab conditions and runs a little higher.
BMR is driven mainly by lean body mass, followed by age, sex, and body size — muscle tissue burns more calories at rest than fat tissue, which is why two people of the same weight can have meaningfully different BMRs.
Enter your basic stats to see BMR calculated three ways:
A 28-year-old man, 175 cm, 72 kg: Mifflin-St Jeor BMR = 10×72 + 6.25×175 − 5×28 + 5 = 720 + 1,093.75 − 140 + 5 ≈ 1,679 kcal/day. With 20% body fat (57.6 kg lean mass), Katch-McArdle gives 370 + 21.6×57.6 ≈ 1,614 kcal/day.
| Term | What it measures | Typical relation |
|---|---|---|
| BMR | Calories at complete rest, strict fasted conditions | Baseline, usually the lowest figure |
| RMR | Calories at rest, less strict conditions | Usually 5–10% higher than BMR |
| TDEE | BMR/RMR × activity level | 1.2×–1.9× BMR depending on activity |
The three formulas usually land within a few percent of each other, but pick the one that fits your situation:
Benefits: gives a fast, free estimate of resting energy needs, and comparing formulas highlights how sensitive the estimate is to muscle mass. Limitations: all formulas are population averages; actual BMR can be affected by thyroid function, medications, pregnancy, and genetics, and can only be measured precisely with indirect calorimetry.
BMR varies widely with age, sex, height, and weight, but commonly falls between 1,200–1,800 kcal/day for adult women and 1,500–2,200 kcal/day for adult men.
No. BMR is your resting energy need only. Your actual calorie target should be based on TDEE, which adds activity on top of BMR.
Mifflin-St Jeor is generally considered most accurate for the general population; Katch-McArdle can be more accurate if you know your body fat percentage, especially if you're lean or very muscular.
Building muscle through resistance training is the most reliable way to modestly increase resting metabolic rate over time, since muscle tissue burns more calories at rest than fat.
Extended calorie restriction can trigger metabolic adaptation, a partial, usually temporary, reduction in resting energy expenditure beyond what weight loss alone would predict.