Calorie Calculator

Where the daily number comes from

Your calorie target is built in two steps: estimate the energy your body uses at rest, then scale it by how much you move. This calculator uses the Mifflin–St Jeor equation for the first part and a standard activity multiplier for the second.

That gives maintenance calories — the amount that holds your weight steady. Goals adjust from there.

Deficits and surpluses

Roughly 7,700 calories correspond to a kilogram of body mass, so a daily deficit of 500 calories works out to about half a kilo a week. That rate is well tolerated and generally sustainable.

Aggressive deficits look efficient on paper and rarely survive contact with real life. They also cost more lean tissue, leave you hungrier, and make the eventual regain more likely. For weight gain, a smaller surplus of 300–400 calories a day adds mass with less fat than a large one.

Protein, carbs and fat

The macronutrient split shown alongside the target is a reasonable default — 30% protein, 40% carbohydrate, 30% fat — not a rule. Protein is the one worth protecting: it preserves muscle in a deficit and keeps you fuller. Roughly 1.6–2.2 g per kilogram of body weight is the range most evidence supports for people who train.

Why the number won't be exactly right

Calorie estimates carry two layers of error: the equation's margin of about 10%, and the gap between how much people think they eat and how much they actually eat, which studies put between 20% and 40%.

Treat the figure as a hypothesis. Weigh yourself over a fortnight, average the readings, and adjust by 100–200 calories if the trend isn't moving.