TDEE Calculator

History of Energy Expenditure

Estimating daily calorie needs grew from early nutrition science into the BMR and activity-factor models used today.

Atwater and Basal Metabolism

Wilbur Atwater's late-19th-century respiration chamber experiments measured how much energy the body burns at rest and during activity, founding the study of human metabolism.

The idea of a basal metabolic rate — the energy to stay alive — emerged from this work.

Predictive Equations

Through the 20th century, equations such as Harris-Benedict (1919) and later Mifflin-St Jeor (1990) estimated BMR from weight, height, age, and sex without a lab.

Multiplying BMR by an activity factor gives total daily energy expenditure (TDEE).

Activity Multipliers

Standard activity factors — from sedentary (1.2) to extra active (1.9) — were developed to scale BMR to real-life output.

This calculator uses the Mifflin-St Jeor BMR and these multipliers to estimate maintenance calories and targets for losing or gaining weight.