Estimating the calories you burn each day
This calculator uses the Mifflin-St Jeor equation, the current standard for predicting basal metabolic rate from sex, age, height, and weight, and then applies a standard activity multiplier to reach your total daily energy expenditure. That maintenance figure is the number of calories that would keep your weight roughly stable at your current activity level. These results are estimates for general information and are not medical or dietary advice — speak to a doctor or a registered dietitian before making significant changes to what you eat.
How the numbers are built up
BMR covers the energy your body spends at rest. Multiplying it by an activity factor between 1.2 (sedentary) and 1.9 (extra active) adds the cost of moving, working, and training. The multiplier matters more than most people expect: the same person can have a maintenance requirement several hundred calories apart depending purely on how active their week is, which is why choosing the level honestly is the single biggest factor in getting a useful answer.
Using the targets sensibly
Weight change follows a sustained difference between what you eat and what you burn, so the targets shown are maintenance plus or minus 250 or 500 calories a day — a pace of roughly a quarter to half a kilogram a week. Slower changes are easier to keep up and less likely to cost you muscle. Because every equation is an average, the honest test is reality: weigh yourself consistently over two or three weeks, and if nothing is moving, adjust your daily figure by 100–200 calories rather than assuming the formula was right.