Util Tools BMR and TDEE explained
Your BMR (Basal Metabolic Rate) is the energy your body burns at complete rest just to stay alive. Your TDEE (Total Daily Energy Expenditure) is your BMR multiplied by an activity factor to include movement and exercise; it is the number of calories you actually burn in a day. TDEE is the figure you plan your diet around, and this tool estimates it using four research-based formulas.
The Mifflin-St Jeor equation
The Mifflin-St Jeor equation is the most widely recommended BMR formula today, considered more accurate for modern populations than older equations. It uses your weight, height, age, and sex. The calculator also offers alternatives (such as Harris-Benedict and Katch-McArdle, which factors in lean mass) so you can compare, because no formula is exact for every individual.
Eating for loss, maintenance, or gain
Weight change comes down to energy balance. To lose weight, eat below your TDEE; a deficit of about 500 calories a day targets roughly half a kilogram (about one pound) of loss per week. To maintain, eat at your TDEE. To gain muscle, eat a modest surplus combined with strength training. Extreme deficits backfire by costing you muscle and being hard to sustain.
How accurate are calorie calculators?
These formulas are educated estimates, not measurements, and real metabolism varies between people of the same stats. Use the result as a starting point: track your weight and intake for two to three weeks, then adjust your calories up or down based on what actually happens on the scale. Your own data beats any formula.
For general information only, not medical or dietary advice. Consult a professional before making significant changes to your diet.
Last updated: July 2026