How bmr calculator works
Your Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest just to keep you alive — powering breathing, circulation, cell production, and temperature regulation. It is the largest single component of your daily energy expenditure, typically 60 to 70 percent of the calories you use each day.
This calculator uses the Mifflin-St Jeor equation by default, the formula most dietitians now recommend. For men it is 10 times weight (kg) plus 6.25 times height (cm) minus 5 times age (years) plus 5. For women the constant is -161 instead of +5. You can also switch to the older Harris-Benedict equation, which gives slightly higher estimates.
Enter your gender, age, weight in kilograms, and height in centimetres, then choose a formula. The result is your daily calorie floor at rest. To estimate your actual maintenance calories, multiply BMR by an activity factor — try the related Calorie Calculator for that. BMR is an estimate, not a measurement; treat it as a starting point.