Energy Balance
TDEE Calculator
Estimate Total Daily Energy Expenditure and maintenance calories using Mifflin-St Jeor BMR, refined with Katch-McArdle when body fat is available. Activity multipliers range from sedentary (1.2) to competitive (1.9). TDEE is the foundation for calorie planning, fat loss, and lean bulk targets.
System Units
Awaiting Calculator Inputs
Fill in the fields above and hit Calculate to generate your body composition targets.
Formula & Math
Uses Mifflin-St Jeor by default and Katch-McArdle when a body fat estimate is available.
How to Interpret
Treat TDEE as a starting maintenance estimate. Actual maintenance is confirmed by weight trend over time.
Plan Integration
Take these estimations back to the main Strategy Finder assessment, or save them in your tracking logs in the local dashboard.
TDEE Science: Measuring Daily Energy Expenditure
Science & physiological analysis for strategy selection
Reviewed by Divy Yadav, CSCS
Last updated: June 27, 2026 · BodyCompOS Editorial Board
Total Daily Energy Expenditure (TDEE) is the cumulative number of calories your body burns in a 24-hour period. It represents the thermodynamic baseline for all body composition changes. Understanding TDEE requires looking beyond a single predictive number to examine the four distinct components of human metabolism: Basal Metabolic Rate (BMR), Non-Exercise Activity Thermogenesis (NEAT), the Thermic Effect of Food (TEF), and Exercise Activity Thermogenesis (EAT). By assessing these metabolic layers, BodyCompOS establishes a personalized baseline for fat loss deficit sizing or lean mass building surpluses.
1. How to Use & Apply This Target
Use this TDEE estimate as your starting daily calorie intake for weight maintenance. Because predictive equations carry an inherent variance (typically ±10% depending on lean mass share), you must verify this calculation empirically. Track your daily caloric intake and morning body weight for 14 to 28 days. Calculate a weekly rolling average of weight. If your weight remains stable within ±0.2% of body weight, your actual maintenance intake matches your target. Adjust intake only after establishing this real-world baseline.
2. Mathematical Assumptions & Formula Logic
BMR calculations are performed using the Mifflin-St Jeor equation, which incorporates age, height, weight, and sex. When body fat percentage is supplied, the system overrides Mifflin-St Jeor and utilizes the Katch-McArdle formula, which uses lean body mass directly for superior predictive accuracy in active or highly muscled populations. The output is scaled by activity factors ranging from 1.2 (sedentary, desk-bound) up to 1.9 (highly active, competitive athlete) to account for daily energy expenditure variation.
3. Step-by-Step Worked Mathematical Example
Frequently Asked Questions
Q:Why does my TDEE change from week to week?
TDEE is not a static number. Your Non-Exercise Activity Thermogenesis (NEAT) naturally fluctuates based on stress, sleep, daily steps, and calorie intake. During a calorie deficit, the body often unconsciously reduces NEAT to conserve energy, resulting in a slightly lower actual TDEE. This is known as adaptive thermogenesis.
Q:Should I eat my exercise calories back?
Generally, no. The activity multipliers in the TDEE calculator already account for your training sessions. Eating back calories logged by fitness trackers or gym machines often leads to overestimating burn rates and stalling fat loss progress, as those devices frequently overstate exercise energy costs by 20-40%.
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Calculate daily calorie targets for fat loss (cutting at 85% TDEE), lean bulk (108%), aggressive bulk (115%), or recomposition (98%). Conservative multipliers optimize fat mobilization while preserving muscle mass. A practical starting point for body composition strategy planning.
Maintenance Calorie Calculator
Estimate daily maintenance calories (TDEE at net energy balance) using Mifflin-St Jeor BMR with activity factor multipliers. The baseline for all calorie planning — confirmed when weight trend is stable under consistent intake. Foundation for fat loss and lean bulk targets.
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