BMR Calculator - Basal Metabolic Rate Calculator

Calculate your Basal Metabolic Rate to determine how many calories your body burns at rest

BMR Calculator Tool
Enter your details to calculate your BMR using the Harris-Benedict equation

Understanding Basal Metabolic Rate (BMR)

Basal Metabolic Rate (BMR) represents the minimum number of calories your body requires to maintain essential physiological functions while at complete rest. This BMR calculator uses the scientifically validated Harris-Benedict equation to provide accurate estimates for both men and women.

Your BMR accounts for approximately 60-75% of your total daily energy expenditure and includes calories burned for breathing, circulation, cell production, nutrient processing, protein synthesis, and maintaining body temperature. Understanding your BMR is crucial for effective weight management and nutrition planning.

Factors Affecting Your BMR

Primary BMR Factors

Body Size & Composition

Larger bodies and more muscle mass increase BMR

Age

BMR typically decreases by 1-2% per decade after age 20

Gender

Men generally have higher BMR due to more muscle mass

Secondary BMR Influences

Genetics

Inherited traits can affect metabolic rate by 5-10%

Hormones

Thyroid, insulin, and cortisol levels impact metabolism

Environmental Temperature

Extreme temperatures can increase energy expenditure

BMR vs TDEE: Understanding the Difference

BMR (Basal Metabolic Rate)
  • • Calories burned at complete rest
  • • Includes only essential body functions
  • • Measured in controlled laboratory conditions
  • • Represents 60-75% of total daily calories
  • • Used as baseline for calorie calculations
TDEE (Total Daily Energy Expenditure)
  • • BMR + physical activity calories
  • • Includes exercise and daily movement
  • • Accounts for thermic effect of food
  • • Represents total calories burned per day
  • • Used for weight management planning

BMR Activity Level Multipliers

Sedentary

×1.2

Little/no exercise

Light

×1.375

Light exercise 1-3 days/week

Moderate

×1.55

Moderate exercise 3-5 days/week

Very Active

×1.725

Hard exercise 6-7 days/week

Extreme

×1.9

Very hard exercise, physical job

BMR Calculator Frequently Asked Questions

How accurate is the BMR calculator?

The Harris-Benedict equation used in this BMR calculator is accurate within ±10% for most healthy adults. However, individual variations in muscle mass, genetics, and metabolic efficiency can affect actual BMR. For precise measurements, consider indirect calorimetry testing at a medical facility.

Why does BMR decrease with age?

BMR typically decreases by 1-2% per decade after age 20 due to several factors: loss of muscle mass (sarcopenia), decreased physical activity, hormonal changes, and reduced organ function efficiency. Regular strength training and maintaining active lifestyle can help minimize age-related BMR decline.

Can I increase my BMR naturally?

Yes! Build lean muscle through strength training (muscle burns more calories than fat), eat protein-rich foods (higher thermic effect), stay hydrated, get adequate sleep, and consider high-intensity interval training (HIIT). These strategies can boost your metabolic rate by 5-15% over time.