TDEE, Total Daily Energy Expenditure, is the total calories your body burns in 24 hours. It is the foundation for every meaningful calorie target: cut, maintain, or bulk. This guide explains where the number comes from, why two calculators can give you different answers, and how to dial yours in.
The four components of TDEE
- BMR (60-70%), Basal Metabolic Rate. What you'd burn in a coma. Driven by lean mass, age, height and sex. The BMR calculator uses the Mifflin-St Jeor equation.
- TEF (10%), Thermic Effect of Food. The energy used to digest what you eat. Protein has the highest TEF (~25-30%), then carbs (~5-10%), then fat (~3%).
- EAT (5-15%), Exercise Activity Thermogenesis. The calories you burn during deliberate exercise. Smaller than people think.
- NEAT (15-50%), Non-Exercise Activity Thermogenesis. Walking, fidgeting, gesturing, standing. The most variable piece, easily 700 kcal/day between sedentary and constantly-moving people.
Why calculators disagree
Different BMR equations (Mifflin-St Jeor vs Harris-Benedict vs Katch-McArdle) give different starting numbers. Activity multipliers vary by source, some sites use 1.55 for "moderate", others use 1.5 or 1.6. Add it up and you can see 200-400 kcal of variance across calculators.
Use the TDEE calculator as a starting estimate, then validate against real-world data: eat at the estimated TDEE for two weeks, weigh daily, average, and adjust.
NEAT: the secret variable
The single biggest driver of TDEE difference between two similar people is NEAT. A construction worker and an accountant of identical size, age and weight can differ by 800-1,000 kcal/day. NEAT also drops automatically when you cut, fewer fidgets, less spontaneous walking, slower gestures, which is part of why fat loss slows over time.
How accurate is your TDEE estimate?
Within ±10% for most people. To improve accuracy: pick the lower activity multiplier when in doubt, don't eat back watch-reported exercise calories, recalculate every 10 lb of weight change.
What to do with your TDEE
- Eat at TDEE → bodyweight stable over 4 weeks.
- Eat 20% below TDEE → moderate fat loss.
- Eat 10% above TDEE → lean muscle gain.
Combine TDEE with the macro calculator to translate calorie targets into actual food.