TDEE Calculator

TDEE is built in two steps, and both appear in the results. First, BMR — what your body spends at rest — from the Mifflin-St Jeor equation: 10 × weight(kg) + 6.25 × height(cm) − 5 × age, then + 5 for men or − 161 for women. Second, that figure is multiplied by an activity factor: sedentary ×1.2, light ×1.375, moderate ×1.55, intense ×1.725, very intense ×1.9. So TDEE = BMR × factor. Everything downstream — deficits, surpluses, macro splits — rests on this one number, which is worth remembering when you see it quoted to the nearest calorie. It is an estimate multiplied by another estimate, and it deserves to be read with that much precision, not more.

The multiplier does a great deal of work in very little space. It has to cover everything BMR leaves out: structured exercise, walking, standing, fidgeting, housework, commuting, and the energy spent digesting what you eat. Two of those deserve attention. Non-exercise activity — all the movement that is not training — varies enormously between people with similar jobs, and it is the main reason two people with identical inputs genuinely burn different amounts. The thermic effect of food, the cost of digesting and absorbing a meal, adds a further modest share that rises and falls with how much you eat. The factor also describes your whole week, not your best day. Three gym sessions around a desk job is light to moderate, not intense. Choosing one bracket too high is the single largest source of error here — larger than any imprecision in the equation itself.

This is not a number you compute once and keep. It falls as you lose weight, for two reasons at the same time: a smaller body costs less to run, and moving a smaller body costs less per step. Spontaneous daily activity often drifts down during a diet as well. That is why a target that worked for a month can stop working, and why the honest response is to recalculate as your weight changes rather than keep pushing intake down against a stale figure. It moves upward too. More lean mass, more daily movement, or a spell of heavier training all raise it. None of this is a failure of the formula — it is simply what a population average does when the individual it describes changes.

This is a population estimate, not a measurement. The Mifflin-St Jeor equation was fitted to a sample of healthy adults; individual resting expenditure scatters around the line it draws, and the activity factor then multiplies that scatter. Measuring resting expenditure rather than predicting it requires indirect calorimetry in a clinical setting. There is a second, quieter source of error that has nothing to do with the arithmetic: what you actually eat is also measured with error. Portion estimates drift, labels round, and untracked extras accumulate. When a calculated intake and the observed weight trend disagree over several weeks, the tracking is at fault at least as often as the equation. If you use this number at all, use the trend across weeks — not day-to-day changes, which are largely water and gut contents — as the feedback that counts.

The equation behind this page was built on healthy adults and does not extend beyond them. Children and teenagers have needs tied to growth. Pregnancy and breastfeeding add requirements the formula does not model, and are managed through prenatal and postnatal care. Acute illness, recovery from surgery, thyroid and metabolic conditions, and several classes of medication all change energy expenditure in ways five input fields cannot capture. If you have any history of disordered eating, a daily calorie figure from a calculator is a poor thing to anchor on, and a clinician is the right person to talk to. This page explains how the estimate is assembled and where it breaks. It does not tell you how much to eat or what to weigh — those decisions belong with a physician or a registered dietitian.