Free tool

Calorie and macro calculator

This calculator estimates the calories and macronutrients (protein, carbs, fat) to aim for each day based on your profile, activity and goal. It uses the Mifflin-St Jeor formula, one of the most widely used for estimating basal metabolic rate. The result is a starting point, to be adjusted according to how your weight actually changes.

The calculator appears once the page has loaded: sex, age, height, weight, activity and goal give the calories and the grams of protein, carbs and fat to aim for each day.

How it’s calculated

1. Basal metabolic rate

It’s the energy the body burns at rest over a day. Mifflin-St Jeor formula: 10 × weight (kg) + 6.25 × height (cm) − 5 × age, then + 5 for a man or − 161 for a woman.

2. Daily energy expenditure

Basal metabolic rate is multiplied according to activity level.

  • Sedentary · little or no exercise: × 1.2
  • Light · 1 to 3 workouts a week: × 1.375
  • Moderate · 3 to 5 workouts: × 1.55
  • Active · 6 to 7 workouts: × 1.725
  • Very active · hard training every day: × 1.9

3. The goal

Expenditure is then adjusted to the goal.

  • Cut (fat loss): -20%
  • Recomp: -5%
  • Maintenance: no adjustment
  • Bulk: +12%

4. Macros

Protein is set per kilo of bodyweight (2.2 g on a cut, 1.8 g otherwise), fat at around 27 to 28% of calories, and carbs make up the rest. Protein and carbs provide 4 kcal per gram, fat 9 kcal.

An estimate, not a measurement: two people with the same profile can have different needs. Track weight changes over two to three weeks and adjust. This calculator doesn’t replace advice from a doctor or dietitian, especially in case of pregnancy, illness or an eating disorder.

Are you a coach? ALTERO calculates these targets automatically for each of your athletes, based on their profile, and you adjust them as you like. Free for up to 2 athletes. Start for free

Frequently asked questions

How do you calculate your calorie needs?

You first estimate basal metabolic rate (for example with the Mifflin-St Jeor equation), multiply it by activity level to get daily energy expenditure, then adjust it to the goal: a deficit to cut, a surplus to bulk.

How much protein per day for bodybuilding?

This calculator uses 1.8 g per kilo of body weight, and 2.2 g on a cut to preserve muscle. These are common benchmarks in bodybuilding; a coach adjusts them to the individual.

How many calories to cut?

Here, the cut starts from your daily expenditure minus 20 %. Then you check that your weight drops steadily, and adjust if the loss is too fast or stalls.

Why isn’t my weight moving when I’m hitting my calories?

The calculation is an estimate: real needs vary from person to person, and weight fluctuates from day to day (water, salt, digestion). Look at the weekly average over two to three weeks before adjusting by 100 to 200 kcal.

What is the Mifflin-St Jeor formula?

An equation published in 1990 that estimates basal metabolic rate from weight, height, age and sex. It’s among the most widely used today to estimate energy needs.