Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest to maintain basic functions — breathing, circulation, and cell repair. It forms the base of all calorie calculations.

The Mifflin-St Jeor equation, which is the most validated formula for general adults and consistently outperforms older equations like Harris-Benedict in accuracy studies.

Multiply your BMR by your activity factor to get your TDEE (total daily energy expenditure). That final number is your calorie maintenance level. Use our TDEE Calculator to do this automatically.

Yes. BMR decreases with age (roughly 1–2% per decade after 20) and drops significantly during severe caloric restriction due to metabolic adaptation. Preserving muscle mass through resistance training is the most effective way to slow BMR decline.