About TDEE Calculator
What is TDEE?
Total Daily Energy Expenditure (TDEE) is the total number of calories your body burns in a day. It combines your Basal Metabolic Rate (BMR) — the energy your body needs for basic functions like breathing, circulation, and cell production — with the calories burned through physical activity, digestion, and non-exercise movement.
Methodology
TDEE.app supports three peer-reviewed equations for estimating Basal Metabolic Rate. The default is the Mifflin-St Jeor equation, which has been shown to be the most accurate for the general population.
Mifflin-St Jeor (1990)
Developed by Mifflin et al. and validated across a wide range of body types, this equation is recommended by the Academy of Nutrition and Dietetics as the best starting point for estimating resting metabolic rate in healthy adults.
Revised Harris-Benedict (1984)
Originally published by Harris and Benedict in 1919, this equation was revised by Roza and Shizgal in 1984 to improve accuracy. It was the clinical standard for decades and remains widely used. It tends to produce slightly higher estimates than Mifflin-St Jeor.
Katch-McArdle (1996)
The Katch-McArdle formula calculates BMR from lean body mass rather than total body weight, making it more accurate for individuals who know their body fat percentage. Because it uses lean mass, it does not require separate equations for men and women.
Why Mifflin-St Jeor is the default
A 2005 systematic review by Frankenfield et al. compared the predictive accuracy of several BMR equations against indirect calorimetry measurements. The Mifflin-St Jeor equation was found to predict resting metabolic rate within 10% of measured values for the largest proportion of subjects — outperforming both Harris-Benedict and the WHO/FAO/UNU equations.
For people who know their body composition, the Katch-McArdle formula can be more precise since it accounts for the metabolic difference between lean tissue and fat tissue.
Activity multipliers
Once BMR is estimated, it is multiplied by an activity factor to approximate total daily calorie expenditure. The five-level activity scale used by TDEE.app is derived from the original Harris-Benedict research and has been widely adopted in sports nutrition and clinical dietetics.
Activity multipliers range from 1.2 (sedentary) to 1.9 (extra active). These values are population averages — individual variation depends on exercise intensity, duration, body composition, and non-exercise activity thermogenesis (NEAT).
About us
TDEE.app is developed and maintained by Apperitif Limited. The calculator is available as a free web tool, an iOS app, and a Chrome extension.