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About BMR Calculator
Our BMR Calculator helps you determine your Basal Metabolic Rate using three scientifically validated formulas: Mifflin-St Jeor, Harris-Benedict (Revised), and Katch-McArdle. BMR represents the number of calories your body needs at rest to maintain basic physiological functions. The calculator also provides Total Daily Energy Expenditure (TDEE) based on your activity level, helping you understand your daily calorie needs for weight maintenance, loss, or gain.
BMR Calculator
cm
ft
in
1 inch = 2.54 cm
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1 kg = 2.20462 lbs
About BMR
What is BMR?
Basal Metabolic Rate (BMR) is the number of calories your body needs to perform basic, life-sustaining functions at rest. This includes breathing, circulating blood, cell production, and maintaining body temperature. BMR accounts for approximately 60-75% of your total daily calorie expenditure and varies based on age, gender, weight, height, and body composition.
BMR vs. RMR
BMR and Resting Metabolic Rate (RMR) are often used interchangeably, but there is a small difference. BMR is measured under very strict conditions (after 8 hours of sleep, 12 hours of fasting, in a temperature-controlled room), while RMR is measured under less strict conditions and tends to be slightly higher. For practical purposes, both give a similar estimate of your resting calorie needs.
BMR Formulas
Mifflin-St Jeor (Most Accurate for Most People)
Men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) + 5
Women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) − 161
Harris-Benedict (Revised)
Men: BMR = (13.397 × weight in kg) + (4.799 × height in cm) − (5.677 × age) + 88.362
Women: BMR = (9.247 × weight in kg) + (3.098 × height in cm) − (4.330 × age) + 447.593
Katch-McArdle (Best for Lean Individuals)
BMR = 370 + (21.6 × lean body mass in kg)
Requires knowing your body fat percentage to calculate lean body mass.
Activity Levels Explained
Your BMR is multiplied by an activity factor to estimate your Total Daily Energy Expenditure (TDEE):
| Activity Level | Description | Multiplier |
|---|---|---|
| Sedentary | Little or no exercise, desk job | BMR × 1.2 |
| Lightly Active | Light exercise 1-3 days/week | BMR × 1.375 |
| Moderately Active | Moderate exercise 3-5 days/week | BMR × 1.55 |
| Very Active | Hard exercise 6-7 days/week | BMR × 1.725 |
| Extra Active | Very hard exercise, physical job | BMR × 1.9 |
Factors Affecting BMR
- Age: BMR decreases approximately 1-2% per decade after age 20
- Body Size: Larger bodies require more energy to maintain basic functions
- Body Composition: Muscle tissue burns more calories at rest than fat tissue
- Gender: Men typically have higher BMR due to greater muscle mass and larger body size
- Genetics: Some people naturally have a higher or lower BMR
- Hormones: Thyroid hormones significantly influence metabolic rate
- Temperature: Extreme cold or heat can increase BMR as the body works to regulate temperature
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