Formula Sources and Calculation Notes

Last updated: 2026-07-01

This website estimates BMR and TDEE using commonly used calorie-estimation equations. The result is educational and should be treated as a starting estimate.

Mifflin-St Jeor

When body fat percentage is not entered, the calculator estimates BMR using the Mifflin-St Jeor equation. It uses sex, age, height, and weight.

Katch-McArdle

When body fat percentage is entered, the calculator can estimate BMR using lean body mass. This can be useful when body composition differs strongly from the average.

Activity multipliers

The calculator multiplies estimated BMR by the selected activity level to estimate Total Daily Energy Expenditure. Activity multipliers are broad categories and should be adjusted based on real progress.

Macros

Macronutrient estimates are calculated from calorie targets and percentage splits. Protein and carbohydrate estimates use 4 calories per gram, and fat estimates use 9 calories per gram.