How many calories do I burn a day?

How the daily calorie number is built

Total daily energy expenditure is a two-part calculation. First, your resting metabolic rate (BMR) estimates the calories your body burns just to keep you alive at rest — breathing, circulating blood, maintaining temperature. Most calculators, including the TDEE Calculator, use the Mifflin-St Jeor equation, which derives BMR from your sex, age, height and weight.

Second, that BMR is multiplied by an activity factor. The multipliers run from about 1.2 for a sedentary lifestyle (desk job, little exercise) up to roughly 1.9 for very active people (hard physical work or intense daily training). The result is your TDEE: the estimated total calories you burn in a day.

A worked example

Say the Mifflin-St Jeor equation puts someone's BMR at 1,500 calories. If they are lightly active and their activity factor is 1.4, their estimated TDEE is 1,500 × 1.4 = 2,100 calories a day.

Change only the activity level and the number moves a lot. At sedentary (1.2) the same person burns about 1,800 calories; at very active (1.9) they burn about 2,850. That gap — from the same body doing more or less movement — is why two people of identical size can have very different daily totals.

What moves the number, and what maintenance means

Body size and sex matter most: more mass and, on average, male physiology raise BMR. Age lowers it gradually. Day-to-day movement — steps, exercise, physical work — drives the activity factor. That is why daily burn spans a wide band, roughly 1,600 to 3,000 calories across adults.

TDEE represents maintenance: the intake at which weight tends to hold steady. Eating below it generally leads to weight loss over time, and above it to weight gain. This is a description of how energy balance works, not a target — the standard presents these as ranges, not a personal prescription.

This article is general information, not medical or nutritional advice. A doctor or registered dietitian can offer guidance tailored to your individual health and goals.

Why it's an estimate, not a measurement

Equations like Mifflin-St Jeor are population averages. Individual metabolisms vary by about ±10–15% from the predicted figure because of differences in muscle mass, genetics, hormones and other factors the formula can't see.

So treat any calculated TDEE as a starting reference point rather than an exact metabolic reading. Running your own figures in the TDEE Calculator gives you a reasonable baseline; observing how your weight actually responds over several weeks is what tells you where your real number sits.