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BMR Calculator

Calculate your Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE) using the scientifically-validated Mifflin-St Jeor formula. Discover how many calories you burn at rest and with different activity levels. Essential for weight management, nutrition planning, fitness goals, and understanding your metabolism. Perfect for dietitians, personal trainers, athletes, and anyone serious about health and fitness optimization.

Calculate Your BMR

Gender
Age
Weight
Height

Your Results

1,730
calories/day (BMR)

Daily Calorie Needs (TDEE)

🛋️ Sedentary
Little or no exercise
2,076 cal/day
🚶 Light Activity
Light exercise 1-3 days/week
2,379 cal/day
🏃 Moderate Activity
Moderate exercise 3-5 days/week
2,682 cal/day
💪 Very Active
Hard exercise 6-7 days/week
2,984 cal/day
🏋️ Extremely Active
Very hard exercise, physical job
3,287 cal/day

BMR Categories by Age & Gender

Men (calories/day)

Age 20-301800-2000

Peak metabolic years

  • • Higher muscle mass
  • • Active lifestyle
Age 31-501700-1900

Gradual decline begins

  • • Muscle mass starts to decrease
  • • Metabolism slows slightly
Age 51+1600-1800

Lower metabolic rate

  • • Reduced muscle mass
  • • Hormonal changes

Women (calories/day)

Age 20-301500-1700

Peak metabolic years

  • • Hormonal stability
  • • Active lifestyle
Age 31-501400-1600

Metabolic transition

  • • Muscle mass decline
  • • Hormonal changes
Age 51+1300-1500

Post-menopausal changes

  • • Reduced estrogen
  • • Lower muscle mass

How to Calculate BMR

Mifflin-St Jeor Equation

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

Calculation Steps:

  1. 1
    Convert units if necessary
    Weight to kg, height to cm
  2. 2
    Apply the Mifflin-St Jeor formula
    Select appropriate equation based on gender
  3. 3
    Calculate TDEE
    Multiply BMR by activity level factor

Important Considerations

⚠️ Medical Disclaimer

This calculator provides estimates. Consult healthcare professionals for medical advice.

🧬 Individual Variations

BMR can vary by ±15% between individuals

  • • Genetics and metabolism
  • • Body composition differences
  • • Health conditions
💪 Muscle Mass Impact

More muscle = higher BMR

  • • Strength training increases BMR
  • • Muscle burns more calories at rest
  • • Age-related muscle loss
🍽️ Diet Effects

Extreme dieting can lower BMR

  • • Metabolic adaptation
  • • Hormone changes
  • • Sustainable approaches work better
⚕️ Health Conditions

Medical conditions affect BMR

  • • Thyroid disorders
  • • Diabetes
  • • Medications

Example Cases

Case 1: Active Male Office Worker

Input Parameters: Male, 35 years old
Physical: 175cm, 80kg
Activity: Moderate (gym 4x/week)
BMR Result: 1,780 calories/day
TDEE: 2,759 calories/day
Goal: Maintain weight

Use Case: Perfect for meal planning and maintaining current fitness level while working a desk job.

Case 2: Female Weight Loss Goal

Input Parameters: Female, 28 years old
Physical: 165cm, 70kg
Activity: Light (walking 3x/week)
BMR Result: 1,512 calories/day
TDEE: 2,079 calories/day
Goal: Lose 0.5kg/week

Use Case: Create a 500-calorie deficit (1,579 cal/day) for healthy sustainable weight loss.

Frequently Asked Questions

What is BMR (Basal Metabolic Rate)?
BMR is the minimum number of calories your body needs to maintain basic physiological functions like breathing, circulation, and cell production while at rest. It represents the energy required to keep your body functioning if you were to rest for 24 hours.
What's the difference between BMR and RMR?
BMR (Basal Metabolic Rate) is measured under strict conditions after 12 hours of fasting and 8 hours of sleep. RMR (Resting Metabolic Rate) is measured under less restrictive conditions. RMR is typically 10-20% higher than BMR, but the terms are often used interchangeably.
How accurate is this BMR calculator?
This calculator uses the Mifflin-St Jeor equation, which is considered one of the most accurate formulas for calculating BMR. However, individual variations in metabolism, body composition, and health conditions can affect actual BMR by ±10-15%.
How should I use my BMR results?
Use your BMR as a baseline for determining your daily caloric needs. Multiply your BMR by your activity level to get your Total Daily Energy Expenditure (TDEE). This helps with weight management, meal planning, and fitness goals.
What factors affect BMR?
BMR is influenced by age, gender, weight, height, muscle mass, genetics, hormones, climate, and overall health. Men typically have higher BMR than women, and BMR generally decreases with age and increases with muscle mass.

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