Calories a day to keep, lose or gain weight, from your BMR and how active you are
Runs in your browser. Nothing you type is sent anywhere. Updated on 24 Oct 2026.How many calories you need depends on what your body burns at rest (BMR) and how active your week is. This page works out BMR with Mifflin-St Jeor (Am J Clin Nutr, 1990) or the revised Harris-Benedict (Roza and Shizgal, 1984), multiplies it by your activity level, and gives the calories that hold your weight steady, with targets for losing and gaining. Equations predict an average; your needs can differ by a few hundred calories. Not medical advice.
Pick Metric or Imperial, then your Sex, Age, Weight and Height.
Leave The equation on Mifflin-St Jeor (1990), or pick Revised Harris-Benedict (Roza and Shizgal, 1984).
Under Your week, pick the activity level that matches an ordinary week for you.
Read TDEE as the calories that keep your weight steady, then Mild loss (-250), Loss (-500) or Gain (+500) as daily targets.
Basal metabolic rate is not measured here. It is estimated, by an equation fitted to a sample of people, and several such equations exist which disagree by a hundred calories or more about the same body. Naming the one in use is the difference between a figure you can check and a figure you have to trust.
The revised Harris-Benedict equation, from Roza and Shizgal in 1984, is offered too and reads about 50 calories higher for the example above. Katch-McArdle is the third: it uses lean body mass rather than sex and height, so it needs a measured body fat percentage, and it is the better choice for someone who knows theirs.
Loss and gain targets are shown 250 and 500 calories either side of maintenance. The deficit is never printed below 1,500 calories for men or 1,200 for women, and the page says when it has clamped rather than showing a number nobody should eat to.
The rest of the article, and all 6 questions about BMR and TDEE Calculator, are on the BMR and TDEE Calculator page.
Mifflin-St Jeor is the usual modern choice and the default here. Published in the American Journal of Clinical Nutrition in 1990, it was fitted on a larger and more recent sample than the 1919 Harris-Benedict work, and dietetic practice has broadly adopted it for both non-obese and obese adults.
Basal metabolic rate is what the body burns at complete rest, keeping the heart, brain and organs running. Total daily energy expenditure is that figure multiplied by how active the day is, from 1.2 for a desk job to 1.9 for an athlete, and it is the maintenance number that matters for eating.
A deficit of 500 calories a day below maintenance is the common starting point, implying roughly 0.45 kg a week at 7,700 calories to a kilogram of fat. Real loss runs slower as the body adapts. The page refuses to print a target under 1,500 for men or 1,200 for women.
Treat them as a starting estimate, not a measurement. Prediction equations carry an error of ten per cent or more for an individual, and activity multipliers are rougher still. The sensible use is to start at the maintenance figure, track weight for a fortnight, and adjust from what actually happens.
Formula only: no rates or limits are read from an official source.
Still stuck? Ask about BMR and TDEE Calculator and anybody who knows can answer. No account needed.
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