What is BMR?
Your Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest just to keep its essential functions running — breathing, circulation, cell production, and maintaining body temperature. It represents the minimum energy your body needs over 24 hours if you did nothing but rest. BMR depends mainly on your sex, age, height, and weight.
This calculator offers two well-known equations. The Mifflin-St Jeor equation is the modern standard and is generally considered the most accurate for most people. The Harris-Benedict equation is an older, widely used formula. Once your BMR is known, multiplying it by an activity factor estimates your Total Daily Energy Expenditure (TDEE) — the calories you actually use in a typical day, including movement and exercise.
Activity multipliers
Sedentary multiplies BMR by 1.2, light activity by 1.375, moderate by 1.55, very active by 1.725, and extra active by 1.9. These factors turn your resting rate into a realistic daily total.
Frequently asked questions
What is the difference between BMR and TDEE?
BMR is the calories burned at complete rest. TDEE is BMR multiplied by an activity factor and reflects the total calories you burn in a normal day including movement and exercise.
Which formula should I use?
Mifflin-St Jeor is the modern standard and usually the most accurate for the general population. Harris-Benedict is an older equation included here for comparison.
Why does sex affect BMR?
On average, body composition differs between men and women, which the equations account for with different constants. That is why the same height and weight can give different BMR values.
How accurate are these numbers?
They are estimates based on population averages. Individual metabolism varies with muscle mass, genetics, and other factors, so treat the result as a starting reference.
Is my data private?
Yes. All calculations run in your browser. Nothing you enter is uploaded or stored.