Calorie & macronutrient calculator

This calculator works out how many calories you need per day and splits them into protein, fat and carbs for your goal — maintain, lose or gain weight. It uses the Mifflin–St Jeor equation and your activity level. Know your body fat? Add it — the estimate becomes more accurate (Katch-McArdle) and protein is based on lean mass.

Calculate your daily calories and macros

Sex

Fill in the fields on the left — the result appears instantly.

How many calories per day: BMR and TDEE

BMR (basal metabolic rate) is the calories your body burns fully at rest — breathing, heart, brain and keeping warm. It’s estimated with the Mifflin–St Jeor equation from sex, age, height and weight, today’s accuracy standard for healthy adults.

TDEE (total daily energy expenditure) is BMR multiplied by an activity factor: the more you move and train, the higher it is. TDEE is your maintenance calorie level for your current weight.

A deficit to lose and a surplus to gain

To lose weight you need a moderate deficit — the calculator uses −15% of TDEE for steady loss without wrecking muscle or willpower. To gain muscle, a +10% surplus is enough for growth without piling on fat.

Aggressive deficits (−30–40%) work worse: they slow metabolism, cost you muscle and almost always rebound. A ±10% spread between people is normal, so fine-tune the number against 2–3 weeks of weight trend.

Protein, fat and carbohydrate targets

Protein is set at 1.6 g per kg (from lean mass if body fat is known, otherwise from body weight) — enough for satiety and keeping muscle. Fat is about 1 g per kg of body weight for hormonal health. The remaining calories go to carbohydrates, your main fuel for activity.

How the calculator works

Without a body-fat figure it uses Mifflin–St Jeor (from sex, age, height and weight). If you enter body fat, it switches to Katch-McArdle, which derives metabolism from lean mass and is more accurate for lean and muscular people. Activity factors run from 1.2 (sedentary) to 1.9 (very high load).

Frequently asked questions

  • About 15% below your maintenance level (TDEE) — the calculator works this out automatically. This moderate deficit gives steady loss without losing muscle; adjust it against your weight trend over 2–3 weeks.

  • BMR is your basal metabolic rate — calories at complete rest. TDEE is total daily expenditure including activity (BMR × a factor from 1.2 to 1.9). TDEE is your maintenance calorie level.

  • For most active people, around 1.6 g of protein per kilogram. If body fat is known, the calculator bases protein on lean mass — more accurate for lean and muscular people. Fat is about 1 g per kg, the rest is carbs.

  • For healthy adults without body-composition data, Mifflin–St Jeor is the most accurate. If you know your body fat, Katch-McArdle is more accurate because it derives metabolism from lean mass rather than total weight.

  • No. The number is a guide. Keep a weekly average and watch your weight trend. The formulas estimate with a ±10% spread, so real-world results matter more than counting to the calorie.

Match supplements to your goal

Tell us your goal and attach your labs — AI matches supplements to your calories, deficiencies and aims, not “one size fits all”.

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This calculator is for reference and information only and does not replace a doctor or dietitian. Targets are an averaged estimate with a ±10% spread; go by how you feel and your trend.