Basal Metabolic Rate is the number of calories your body burns at complete rest — just to keep you alive (breathing, circulation, cell repair). It accounts for 60–75% of your total daily calorie burn. This calculator uses the Mifflin-St Jeor equation, which is considered the most accurate for most adults.
Total Daily Energy Expenditure adds your activity level to your BMR. If you eat at your TDEE, your weight stays the same. Eating 500 kcal/day below TDEE creates a deficit of 3,500 kcal/week — roughly 1 lb of fat loss per week.
These are estimates — individual metabolism varies. Muscle mass, genetics, sleep, and hormones all affect actual calorie burn. If you're tracking closely, use these numbers as a starting point and adjust by ±100–200 kcal based on real-world results over 2–3 weeks.