Free BMR Calculator
Calculate your Basal Metabolic Rate and Total Daily Energy Expenditure. Find out how many calories you burn at rest and at different activity levels.
Mifflin-St Jeor Formula
The Mifflin-St Jeor equation is considered the most accurate for calculating BMR in modern populations and is recommended by the Academy of Nutrition and Dietetics.
How to Use the BMR Calculator
Enter Your Personal Details
Input your age in years, select your biological sex (male or female), and choose between metric (kg/cm) or imperial (lbs/ft) units for accurate calculations.
Input Your Body Measurements
Enter your current weight and height. For best accuracy, weigh yourself in the morning before eating and measure your height standing straight without shoes.
Select Your Activity Level
Choose the activity level that best matches your typical week: sedentary (desk job), lightly active (1-3 days exercise), moderate (3-5 days), very active (6-7 days), or extra active (physical job + training).
Review Your BMR and TDEE Results
View your Basal Metabolic Rate (calories burned at rest) and Total Daily Energy Expenditure for each activity level. Use these numbers to plan your calorie intake for weight loss, maintenance, or gain.
Pro tip: Your data is processed entirely in your browser. Nothing is sent to any server, ensuring complete privacy.
Understanding Your Basal Metabolic Rate
Your Basal Metabolic Rate (BMR) represents the minimum number of calories your body needs to function while at complete rest. This includes essential processes like breathing, blood circulation, cell production, and maintaining body temperature. BMR typically accounts for 60-75% of your total daily energy expenditure, making it the foundation for understanding your caloric needs.
Why BMR Matters for Weight Management
Understanding your BMR is crucial for effective weight management. To lose weight, you need to consume fewer calories than your Total Daily Energy Expenditure (TDEE). A safe deficit is typically 500 calories per day, which leads to approximately 1 pound of weight loss per week. However, consuming too few calories can actually slow your metabolism, making weight loss harder.
Activity Level Multipliers
- Sedentary (1.2): Little to no exercise, desk job
- Lightly Active (1.375): Light exercise 1-3 days per week
- Moderately Active (1.55): Moderate exercise 3-5 days per week
- Very Active (1.725): Hard exercise 6-7 days per week
- Extra Active (1.9): Very hard exercise, physical job, or training twice daily
Frequently Asked Questions
What is BMR (Basal Metabolic Rate)?
BMR is the number of calories your body needs to perform basic life-sustaining functions while at complete rest. This includes breathing, circulation, cell production, nutrient processing, and protein synthesis. BMR accounts for about 60-75% of your total daily calorie expenditure.
What is the difference between BMR and TDEE?
BMR (Basal Metabolic Rate) is the calories burned at rest, while TDEE (Total Daily Energy Expenditure) includes BMR plus calories burned through physical activity, digestion, and non-exercise movement. TDEE = BMR × Activity Multiplier.
How accurate is the Mifflin-St Jeor formula?
The Mifflin-St Jeor equation is considered the most accurate BMR formula for modern populations, predicting actual BMR within 10% for most people. It was developed in 1990 and is recommended by the Academy of Nutrition and Dietetics over older formulas like Harris-Benedict.
What factors affect BMR?
Key factors affecting BMR include: age (BMR decreases with age), muscle mass (more muscle = higher BMR), body size (larger bodies burn more calories), gender (men typically have higher BMR), genetics, hormones (especially thyroid), and body temperature.
How can I increase my BMR?
To increase BMR: build muscle through strength training, stay active throughout the day, get adequate sleep, eat enough protein, stay hydrated, and avoid extreme calorie restriction which can lower BMR. High-intensity interval training (HIIT) may also temporarily boost metabolism.
Related Tools
Calculate your BMI (Body Mass Index) instantly. Get your health category (underweight, normal, overweight, obese) with personalized insights. Metric & imperial units.
Calculate your daily caffeine intake and see how long caffeine stays in your system.
Convert your dog's age to human years. Account for breed size for more accurate results.
Calculate your Total Daily Energy Expenditure (TDEE) and daily calorie needs. Get personalized recommendations for weight loss, maintenance, or muscle gain with macro breakdowns.