What is TDEE?
TDEE stands for Total Daily Energy Expenditure. It's the total number of calories your body burns in 24 hours — including everything from running marathons to sitting at your desk to breathing while you sleep.
Knowing your TDEE is the foundation of any honest conversation about weight loss, weight gain, or weight maintenance. Without it, calorie targets are guesses. With it, the math becomes actual math.
How TDEE is calculated
TDEE breaks down into four components: Basal Metabolic Rate (BMR — 60-75% of TDEE), physical activity (15-30%), Thermic Effect of Food (TEF — about 10%), and Non-Exercise Activity Thermogenesis (NEAT) — the wildcard that can vary by 2,000+ calories per day between two people of similar size.
Our calculator uses the Mifflin-St Jeor equation to estimate BMR, then multiplies by an activity factor to estimate TDEE.
Activity levels, explained
The biggest source of error in any TDEE calculation is choosing the wrong activity level. People consistently overestimate. Golden rule: when in doubt, pick the lower category.
TDEE and weight loss medications
For people whose biology fights aggressively against weight loss, traditional calorie deficits often fail. GLP-1 medications like semaglutide and tirzepatide work partly by quieting biological pushback mechanisms — reducing appetite, slowing gastric emptying, and reducing metabolic adaptation. In clinical trials, people on semaglutide ate roughly 30% fewer calories per day without being told to restrict.