BMR Calculator

Calculate your Basal Metabolic Rate — the calories your body burns at rest — using the clinically validated Mifflin-St Jeor equation.

What Is BMR and Why It Matters

Your Basal Metabolic Rate (BMR) is the number of calories your body needs to maintain essential functions — breathing, blood circulation, organ function, cell production — while at complete rest for 24 hours. It's your body's minimum fuel requirement just to stay alive.

BMR vs. TDEE: What's the Difference?

BMR is calories burned at complete rest. TDEE (Total Daily Energy Expenditure) multiplies your BMR by an activity factor to account for exercise and daily movement. TDEE is the number you should actually eat around to maintain your weight.

The Mifflin-St Jeor Equation

This calculator uses the Mifflin-St Jeor equation, considered the most accurate for most people by the American Dietetic Association:

  • Men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5
  • Women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161

Average BMR by Age and Sex (American Reference)

Age RangeAverage Male BMRAverage Female BMR
18–251,750–1,9001,400–1,550
26–351,700–1,8501,350–1,500
36–501,600–1,7501,300–1,450
51–651,500–1,6501,200–1,350

Frequently Asked Questions

BMR is the number of calories your body needs to perform basic life-sustaining functions at complete rest — breathing, circulation, temperature regulation, and cell production. It's your metabolic baseline.

BMR is calories at rest. TDEE adds calories from daily activities and exercise. If you work a desk job and walk occasionally, multiply your BMR by ~1.375. If you exercise 5 days/week, use ~1.55. TDEE is what you should eat to maintain weight.

Yes. BMR generally decreases 1–2% per decade after age 20, primarily due to loss of muscle mass (sarcopenia). Resistance training can slow this decline significantly by preserving muscle tissue.

Build muscle through resistance training (muscle burns more calories at rest than fat), eat enough protein (0.7–1g per lb of body weight), stay hydrated, and avoid extreme calorie restriction which can lower your BMR as your body adapts.