TDEE Calculator

BMR (Basal Metabolic Rate) is the calories burned at complete rest - lying still, fasting, in a thermoneutral environment. It represents roughly 60-75% of most people's total daily calorie burn. TDEE adds the energy burned through all daily activity including walking, digesting food (the thermic effect), and exercise. TDEE is the number that determines whether you gain, lose, or maintain weight.

Mifflin-St Jeor uses weight and height as proxies for metabolic mass. Individuals with above-average muscle mass have higher resting energy expenditure per pound of body weight than average because muscle tissue burns more calories at rest than fat tissue. For lean, muscular individuals, the formula may underestimate BMR by 5-10%.

Yes. TDEE decreases as body weight drops because there is less mass to maintain. Failing to recalculate TDEE after significant weight loss (more than 5-10% of body weight) is a common reason fat loss stalls - the deficit has shrunk or disappeared. Recalculate every 4-8 weeks during an active weight-loss phase.

Fitness trackers estimate total calorie burn using heart rate, step count, and proprietary algorithms that vary by manufacturer. These estimates carry their own errors (typically 10-20%). Formula-based TDEE and device-based TDEE are both approximations. Use whichever you track consistently over time, rather than switching between methods, and validate against real weight change.