Your Basal Metabolic Rate (BMR) represents the minimum calories your body needs to maintain basic functions like breathing, circulation, and cell production while at complete rest. This BMR calculator uses scientifically validated formulas to help you understand your metabolism and plan your nutrition for weight loss, maintenance, or muscle gain.
BMR Analysis (30yo Male, 70kg, 175cm):
Your BMR accounts for 60-75% of daily calories - even sleeping burns energy for breathing, circulation, and cell repair.
Input your gender, age, weight, and height. Choose metric (kg/cm) or imperial (lb/ft) units.
Choose your typical weekly exercise frequency to calculate TDEE accurately.
If known, enter your body fat percentage for the more accurate Katch-McArdle calculation.
Select whether you want to lose weight, maintain, or build muscle to get your target calories.
The Mifflin-St Jeor equation is considered the most accurate for calculating BMR. TDEE (Total Daily Energy Expenditure) is calculated by multiplying BMR by an activity factor.
BMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age + s
BMR accounts for about 60-75% of your total daily calorie expenditure - it's the calories you burn just being alive.
The Mifflin-St Jeor formula is generally more accurate for modern populations than the older Harris-Benedict equation.
To lose weight, create a calorie deficit of 500-750 calories below your TDEE for safe, sustainable weight loss of 0.5-1kg per week.
Never eat below your BMR for extended periods - this can slow your metabolism and lead to muscle loss.
Your BMR naturally decreases with age (about 2% per decade after 20), which is why maintaining muscle mass is important.
If you know your body fat percentage, the Katch-McArdle formula provides the most accurate BMR calculation.
Your BMR is the foundation of your daily calorie needs. Understanding it helps you make informed decisions about nutrition, weight management, and fitness goals.
Basal Metabolic Rate (BMR) is the number of calories your body needs to perform basic life-sustaining functions like breathing, circulation, cell production, and nutrient processing while at complete rest. It represents 60-75% of your total daily energy expenditure.
The Mifflin-St Jeor equation (1990) is the most widely recommended formula: Men: BMR = 10×weight(kg) + 6.25×height(cm) - 5×age + 5. Women: BMR = 10×weight(kg) + 6.25×height(cm) - 5×age - 161. This formula is preferred by dietitians and nutritionists.
While BMR measures calories burned at rest, TDEE (Total Daily Energy Expenditure) includes all calories burned through activity. TDEE = BMR × Activity Factor. For weight loss, create a deficit from TDEE, not BMR. Never eat below your BMR consistently.
Multiply your BMR by: 1.2 (Sedentary), 1.375 (Light exercise 1-3 days), 1.55 (Moderate 3-5 days), 1.725 (Hard exercise 6-7 days), or 1.9 (Very hard exercise + physical job). These factors convert BMR to TDEE.
The original Harris-Benedict formula (1918) tends to overestimate calories by 5-10%: Men: 88.362 + 13.397×weight + 4.799×height - 5.677×age. Women: 447.593 + 9.247×weight + 3.098×height - 4.33×age. Still useful for comparison.
If you know your body fat percentage, Katch-McArdle is most accurate: BMR = 370 + 21.6 × Lean Body Mass (kg). This formula accounts for body composition, making it ideal for athletes and those who've measured their body fat.
Data sourced from trusted institutions
All formulas verified against official standards.