TDEE Calculator

TDEE stands for Total Daily Energy Expenditure — the total number of calories your body burns in a day. It combines your basal metabolic rate (the energy needed to keep you alive at rest), the food you digest, everyday movement, and exercise. Eating around your TDEE keeps your weight roughly stable, which is why it is also called your maintenance calories.

This calculator first estimates your basal metabolic rate (BMR) with the Mifflin-St Jeor equation, which uses weight, height, age, and sex. If you enter a body fat percentage, it switches to the Katch-McArdle formula, which estimates BMR from lean body mass instead. That BMR is then multiplied by an activity factor between 1.2 (sedentary) and 1.9 (extra active). These are the same published formulas the Fitzenia app uses for its starting estimate.

BMR (basal metabolic rate) is the energy your body needs at complete rest — breathing, circulation, and basic cell function. TDEE is your BMR plus everything else you do: walking, training, fidgeting, and digesting food. TDEE is the number that matters for setting calorie targets, because you do not spend your day at complete rest.

Formula-based calculators are estimates built on population averages, so your true energy expenditure can differ noticeably. Activity levels are easy to misjudge, and daily movement varies a lot from person to person. Treat the result as a starting point: follow your weight trend for two to four weeks and adjust your intake based on what actually happens.

Adaptive TDEE flips the approach: instead of predicting your expenditure from a formula once, it back-calculates it from real data — what you log eating and how your weight actually trends over time. The Fitzenia app uses this approach, re-estimating your energy needs from your own food log and weight entries so your calorie target reflects your real life instead of a population average.

A common starting point is a moderate deficit of roughly 300–500 kcal below your TDEE, which for many people works out to about 0.25–0.5 kg (0.5–1 lb) per week. Larger deficits look faster on paper but are harder to sustain and make holding on to muscle harder. This is general information, not medical advice — consider consulting a qualified professional before making significant changes to your diet.

Yes. Formula-based TDEE depends on your body weight, so the estimate drifts as you lose or gain — recalculating every few weeks keeps it useful. Alternatively, an adaptive tracker like Fitzenia re-estimates your energy needs from what you actually eat and how your weight trends, so the target keeps up as your body changes.