What TDEE Actually Tells You
Your Total Daily Energy Expenditure is the total number of calories your body burns in 24 hours. It combines four components: Basal Metabolic Rate (BMR — calories burned at rest just keeping you alive, roughly 60–70% of total), the Thermic Effect of Food (digesting food burns 8–10% of calories consumed), Non-Exercise Activity Thermogenesis or NEAT (unconscious movement like fidgeting, standing, walking — highly variable between individuals), and Exercise Activity Thermogenesis (deliberate workouts — often overestimated).
The reason NEAT matters so much: two people of identical height, weight, and workout frequency can have TDEEs 300–500 calories apart based solely on how much they move during their non-exercise hours. Someone who walks throughout the day at a standing desk burns dramatically more than someone who sits 10 hours straight, even if both "go to the gym."
Which TDEE Formula Is Most Accurate?
This calculator uses three formulas. Mifflin-St Jeor (1990) is the gold standard for most people, validated by the Academy of Nutrition and Dietetics with an average error of about 10%. Harris-Benedict (revised 1984) tends to overestimate by 5% but is widely used in clinical settings. Katch-McArdle is the most accurate formula if you know your body fat percentage, because it calculates from lean body mass rather than total weight — making it the best choice for athletes and muscular individuals whose BMR is often underestimated by weight-only formulas.
How to Use TDEE to Actually Reach Your Goal
Losing 1 pound of fat requires a cumulative deficit of approximately 3,500 calories. A 500 calorie/day deficit below your TDEE produces roughly 1 pound of weekly fat loss. A 1,000 calorie/day deficit produces 2 pounds. Most experts recommend not exceeding 1 pound/week for sustained results — larger deficits increase muscle loss, hunger, and the risk of metabolic adaptation (your body reduces TDEE in response to undereating).
The most common mistake: using your TDEE as a "permission slip" to eat exactly that amount. Your TDEE is an estimate with a ±10% error margin. Weigh yourself daily, take the 7-day average, and track it weekly. If your weight isn't moving in the right direction after 2 weeks at your target calories, adjust by 100–150 calories and repeat. Real data beats any formula.