Basal metabolic rate is an estimate of the energy your body uses to support essential functions at rest. This calculator uses the Mifflin-St Jeor equation and can apply an activity factor to produce an estimated total daily energy expenditure. The distinction matters: BMR is not a complete daily calorie target because ordinary movement, exercise, digestion, and recovery also require energy.
Treat the result as a starting estimate and compare it with real-world weight and energy trends over several weeks. Activity categories are broad, and factors such as muscle mass, sleep, stress, illness, medications, and changes in spontaneous movement can shift actual needs. Avoid using a calculator result to justify extreme restriction or an aggressive surplus without appropriate professional support.
BMR estimates resting energy needs. TDEE adds the energy associated with activity and daily living, so it is closer to a total daily maintenance estimate when the activity selection fits your routine.
It uses body weight, height, age, and a sex-specific constant to estimate resting energy expenditure. Like all predictive equations, it describes an average relationship and may differ from an individual measurement.
The activity factor may not match your actual movement, food logging may be incomplete, or your daily activity may change with fatigue and dieting. Compare consistent inputs with longer-term trends before adjusting.
Recalculate after a meaningful change in weight, age, or routine rather than every day. Use the same method and review trends over time to avoid reacting to normal fluctuations.