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Macro calculator for calories, protein, carbs and fat

Enter your age, height, weight, how active you are and your goal. You get a daily calorie target and how many grams of protein, carbs and fat to eat, worked out with the Mifflin-St Jeor equation. Nothing is saved and you don't need an account.

Updated November 2026
Units
Sex
Daily target1,560caloriesProtein137 g35% of caloriesCarbs156 g40% of caloriesFat43 g25% of caloriesMaintenance 1,950 calories, resting 1,422.Plan your meals in Affili-Fit

How the macro calculator works

  1. Resting calories (BMR). The Mifflin-St Jeor equation: 10 × weight in kg + 6.25 × height in cm − 5 × age, then + 5 for men or − 161 for women.
  2. Maintenance calories (TDEE). BMR times an activity factor from the table below.
  3. Goal. To lose fat, eat 20% below maintenance. To build muscle, eat 20% above it. The target never goes below 1,200 calories for women or 1,500 for men.
  4. Protein. 2.0 g per kg of body weight when losing fat, 1.8 g when building muscle and 1.6 g when maintaining, capped at 35% of calories so the number stays sensible for heavier bodies.
  5. Fat. 25% of calories.
  6. Carbs. Whatever calories are left, divided by 4.
Activity levelFactor
Mostly sitting1.2
Exercise 1 to 3 days a week1.375
Exercise 3 to 5 days a week1.55
Hard exercise 6 to 7 days1.725
Physical job or twice a day1.9

Worked example

A 35-year-old woman, 5 ft 5 in (165 cm) and 160 lb (72.6 kg), who exercises lightly 1 to 3 days a week and wants to lose fat:

  • BMR: 1,422 calories a day
  • Maintenance: 1,422 × 1.375 = about 1,950 calories
  • Fat loss target: 20% less, 1,560 calories
  • Protein: 2.0 g × 72.6 kg = 145 g, capped at 35% of calories: 137 g
  • Fat: 25% of 1,560 calories ÷ 9 = 43 g
  • Carbs: the remaining calories ÷ 4 = 156 g

At 1,560 calories that is about 35% protein, 40% carbs and 25% fat. Spread over three meals and a snack, it is roughly 30 to 35 g of protein each time.

How to hit your macros

  • Build each meal around a protein first, then add carbs and a little fat.
  • Plan the week ahead so you aren't guessing at 7 pm. Cooking in batches makes this easier.
  • Weigh foods for the first week or two. Portions eyeballed by hand often run large.
  • Check your weight trend after two to three weeks and move calories by 100 to 200 if needed.

Need more detail on protein alone? The protein calculator gives a range for your situation and explains where each number comes from.

In the Affili-Fit app, you set your goal and the app works out a daily calorie target with the same Mifflin-St Jeor equation, plans a week of meals and logs your calories, protein, carbs and fat as you eat. See the meal planner with grocery list, or start the 7-day free trial.

Limits of any macro calculator

Formulas estimate the average person with your stats. Muscle mass, health conditions, medication and sleep all move your real number up or down, so use the result as a first target and let your weight trend correct it. The calculator is for adults aged 18 to 80 and is not medical advice.

FAQ

Common questions

What are macros?

Macros, short for macronutrients, are the three nutrients that supply calories: protein and carbohydrates have 4 calories per gram, and fat has 9. A macro target splits your daily calories into grams of each.

How accurate is this macro calculator?

It uses the Mifflin-St Jeor equation, which in a 2005 review of energy equations predicted resting calories within 10% of measured values for most adults, more often than other common formulas. Treat the result as a starting point: weigh yourself for two to three weeks and adjust calories by about 100 to 200 a day if your weight isn't moving the way you want.

What macro ratio should I use to lose weight?

Your calorie target matters most for weight loss. Within it, more protein helps you keep muscle and feel full, so this calculator sets protein at 2.0 grams per kilogram of body weight when losing fat, fat at 25% of calories and carbs as the rest. For a woman of average size losing fat, that lands near 35% protein, 40% carbs and 25% fat.

Should I count macros or just calories?

Calories decide whether you lose or gain weight. Macros decide more of what that weight is, muscle or fat, and how full you feel. If tracking everything is too much, count calories and protein and let carbs and fat fall where they do.

Who shouldn't use a macro calculator?

It is made for healthy adults aged 18 to 80. If you are pregnant or breastfeeding, under 18, have kidney disease, diabetes or a history of eating disorders, ask a doctor or registered dietitian for your targets instead.

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