Basal Metabolic Rate Calculator
Calculate basal metabolic rate with our free science calculator. Uses standard scientific formulas with unit conversions and explanations.
Formula
Mifflin-St Jeor: BMR = (10 x weight_kg) + (6.25 x height_cm) - (5 x age) + s
Where s = +5 for males and -161 for females. Weight is in kilograms, height in centimeters, age in years. TDEE = BMR x Activity Multiplier (1.2 sedentary to 1.9 very active). The Mifflin-St Jeor equation is recommended by the Academy of Nutrition and Dietetics as the most accurate for healthy adults.
Worked Examples
Example 1: BMR for a 30-Year-Old Male
Problem: Calculate BMR for a 30-year-old male, 175 cm tall, weighing 80 kg, moderately active.
Solution: Mifflin-St Jeor: BMR = (10 x 80) + (6.25 x 175) - (5 x 30) + 5\nBMR = 800 + 1093.75 - 150 + 5 = 1,748.75 kcal/day\nTDEE = 1,749 x 1.55 (moderate activity) = 2,711 kcal/day
Result: BMR = 1,749 kcal/day | TDEE = 2,711 kcal/day
Example 2: BMR for a 25-Year-Old Female
Problem: Calculate BMR for a 25-year-old female, 163 cm tall, weighing 60 kg, lightly active.
Solution: Mifflin-St Jeor: BMR = (10 x 60) + (6.25 x 163) - (5 x 25) - 161\nBMR = 600 + 1018.75 - 125 - 161 = 1,332.75 kcal/day\nTDEE = 1,333 x 1.375 (light activity) = 1,833 kcal/day
Result: BMR = 1,333 kcal/day | TDEE = 1,833 kcal/day
Frequently Asked Questions
What is Basal Metabolic Rate (BMR)?
Basal Metabolic Rate is the number of calories your body burns at complete rest to maintain basic life-sustaining functions like breathing, circulation, cell production, and nutrient processing. BMR accounts for about 60-75% of your total daily energy expenditure. It is measured under strict resting conditions: after 12 hours of fasting, 8 hours of sleep, in a temperature-neutral environment. BMR is different from Resting Metabolic Rate (RMR), which is slightly higher because it is measured under less restrictive conditions. Understanding your BMR is the foundation for calculating your total caloric needs.
Is Basal Metabolic Rate Calculator free to use?
Yes, completely free with no sign-up required. All calculators on NovaCalculator are free to use without registration, subscription, or payment.
How accurate are the results from Basal Metabolic Rate Calculator?
All calculations use established mathematical formulas and are performed with high-precision arithmetic. Results are accurate to the precision shown. For critical decisions in finance, medicine, or engineering, always verify results with a qualified professional.
Can I use the results for professional or academic purposes?
You may use the results for reference and educational purposes. For professional reports, academic papers, or critical decisions, we recommend verifying outputs against peer-reviewed sources or consulting a qualified expert in the relevant field.
How do I get the most accurate result?
Enter values as precisely as possible using the correct units for each field. Check that you have selected the right unit (e.g. kilograms vs pounds, meters vs feet) before calculating. Rounding inputs early can reduce output precision.
Can I share or bookmark my calculation?
You can bookmark the calculator page in your browser. Many calculators also display a shareable result summary you can copy. The page URL stays the same so returning to it will bring you back to the same tool.