Free BMR Calculator
Enhanced BMR Calculator
Calculate your Basal Metabolic Rate with personalized insights and recommendations
Most accurate for most people
This determines your Total Daily Energy Expenditure (TDEE)
How to Use the BMR Calculator
Our advanced BMR calculator helps you determine your Basal Metabolic Rate - the number of calories your body needs to perform basic life-sustaining functions at complete rest. Understanding your BMR is crucial for weight management, diet planning, and achieving fitness goals. The calculator offers three scientifically validated formulas to ensure accuracy for different body types and fitness levels. Whether you're looking to lose weight, gain muscle, or maintain your current physique, knowing your BMR provides the foundation for effective calorie planning.
Select your preferred calculation formula (Mifflin-St Jeor is recommended for most people)
💡 Measurement Tips
For most accurate results, measure your weight in the morning before eating or drinking, and use your most recent body composition data if available. For body fat percentage, consider using calipers or professional scanning for better accuracy.
What the BMR Calculator Calculates
The Basal Metabolic Rate (BMR) calculator determines the minimum number of calories your body requires to maintain vital functions such as breathing, circulation, cell production, and temperature regulation while at complete rest. This calculation forms the foundation for understanding your Total Daily Energy Expenditure (TDEE). Our calculator provides results using three different scientific formulas: the modern Mifflin-St Jeor equation (most accurate for general population), the classic Harris-Benedict equation (older but still widely used), and the specialized Katch-McArdle formula (most accurate when body fat percentage is known). Beyond just providing a calorie number, the calculator interprets your results according to established metabolic classifications, helps you understand how factors like age, gender, and body composition affect your metabolism, and provides insights for weight management strategies based on your metabolic profile.
Example BMR Calculations
Average Male Example
Input Values
BMR Result
This BMR of 1785 calories/day is typical for a 35-year-old male of this size using the Mifflin-St Jeor formula. To maintain weight with light activity, this person would need approximately 2142 calories daily (BMR × 1.2).
Average Female Example
Input Values
BMR Result
This BMR of 1394 calories/day is typical for a 32-year-old female of this size using the Mifflin-St Jeor formula. For weight loss of 0.5kg per week, a calorie intake of approximately 1200-1400 calories daily would be recommended.
Athlete Example with Katch-McArdle
Input Values
BMR Result
This higher BMR of 1932 calories/day reflects the high muscle mass of an athletic individual using the Katch-McArdle formula. With intense daily training, this athlete might need 3300-3700 total calories daily to maintain energy balance.
💡 Applying Your BMR Results
Remember that your BMR is just the starting point for understanding your calorie needs. To determine your total daily calorie requirements, multiply your BMR by an activity factor based on your lifestyle: Sedentary (little exercise) × 1.2; Lightly active (light exercise 1-3 days/week) × 1.375; Moderately active (moderate exercise 3-5 days/week) × 1.55; Very active (hard exercise 6-7 days/week) × 1.725; Extremely active (very hard exercise, physical job) × 1.9. Adjust based on your goals and progress.
Frequently Asked Questions
Still have questions about BMI calculations?
Try the CalculatorBMR Formulas & Scientific Background
Understanding the mathematical and scientific foundation behind BMR calculations and metabolic rate estimation
Formula
Mifflin-St Jeor Formula (2005)
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 Formula (1919)
Men: BMR = 88.362 + (13.397 × weight in kg) + (4.799 × height in cm) - (5.677 × age in years) | Women: BMR = 447.593 + (9.247 × weight in kg) + (3.098 × height in cm) - (4.330 × age in years)
Katch-McArdle Formula
BMR = 370 + (21.6 × lean body mass in kg) | Lean Body Mass = weight in kg × (100 - body fat percentage) ÷ 100
Scientific Background
Basal Metabolic Rate represents the energy expenditure of vital physiological functions at complete rest in a thermoneutral environment. The concept evolved from early calorimetry studies in the 19th century. The Harris-Benedict equation, developed in 1919, was the standard for decades but was found to overestimate BMR by about 5% in modern populations. The Mifflin-St Jeor equation, published in 2005, provides more accurate estimates for contemporary adults. The Katch-McArdle formula is unique in accounting for body composition by using lean body mass rather than total weight, making it particularly accurate for athletes and those with known body fat percentages. BMR typically accounts for 60-75% of total daily energy expenditure in relatively sedentary individuals.
Medical Disclaimer
This BMR calculator is for informational and educational purposes only and is not intended to replace professional medical advice, diagnosis, or treatment. Metabolic rate can be affected by numerous factors including thyroid function, medications, medical conditions, and genetic factors. The calculations provided are estimates based on population averages and may not accurately reflect your individual metabolic needs. Always consult with a qualified healthcare provider, nutritionist, or dietitian before making any significant changes to your diet, exercise routine, or lifestyle based on these calculations.