Macro Calculator — Daily Protein, Carbs & Fat Split

This free macro calculator works out your daily protein, carbohydrate, and fat targets in grams based on your calorie goal. A common evidence-based split sets protein at about 2 grams per kilogram of body weight, fat at roughly 25% of total calories, and fills the rest with carbohydrates. Protein leads because it preserves muscle in a deficit and is the most satiating macro. Adjust the split for cutting or bulking. All calculations run locally in your browser, so your details stay private.

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Carbs
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Fat
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How are macros calculated?

Macronutrients (macros) are the three main categories of nutrients that provide calories: protein (4 kcal/g), carbohydrates (4 kcal/g), and fat (9 kcal/g). This calculator distributes your daily calorie target across all three based on standard evidence-based ratios.

Protein: 2 g per kg of body weight (higher end of evidence-based range, suitable for active individuals and those preserving muscle during fat loss).
Fat: 25% of total calories.
Carbohydrates: Remainder of calories after protein and fat are allocated.

Protein calories = weight × 2 × 4. Fat calories = total × 0.25. Carb calories = total − protein cal − fat cal. Carb grams = carb calories ÷ 4. These ratios suit general health and body composition goals. Athletes may need higher protein (2.2–3 g/kg); low-carb dieters shift fat higher and carbs lower; endurance athletes may need more carbs.

Related tools

Calorie calculator → BMI calculator → Ideal weight →

Related Guide: Learn more about TDEE and metabolism

How macros are split

Total calories decide weight change; macronutrient split decides body composition and how you feel getting there. A common evidence-based starting point sets protein at ~2 g per kg of body weight, fat at ~25% of total calories, and fills the remainder with carbohydrates. Protein and carbs provide 4 kcal/g, fat 9 kcal/g — which is why fat targets are set by percentage, not grams.

Why protein leads

Protein preserves muscle in a calorie deficit, has the highest thermic effect (your body burns ~25% of its calories just digesting it) and is the most satiating macro — making a cut far easier to sustain. Endurance athletes can lower protein slightly and raise carbs; strength athletes in a bulk often hold protein high and add carbs around training.

Cutting vs bulking

For fat loss, keep protein high and trim mostly carbs and some fat. For lean gains, add a modest calorie surplus that is mostly carbohydrate to fuel training. Fat should rarely drop below ~20% of calories, since it underpins hormone production and the absorption of fat-soluble vitamins.

⚠️ Common Mistakes to Avoid

Frequently asked questions

What is a macro calculator and what does it do?

A macro calculator splits your daily calorie target into grams of protein, carbohydrate, and fat. Total calories drive weight change, while the macronutrient split influences body composition, satiety, and training performance.

How are my macros calculated?

A common evidence-based starting point sets protein at about 2 grams per kilogram of body weight, fat at roughly 25% of total calories, and fills the remaining calories with carbohydrates. Protein and carbs provide 4 calories per gram, fat 9.

Why is protein set first in the macro split?

Protein leads because it preserves muscle in a calorie deficit, has the highest thermic effect (your body burns about 25% of its calories digesting it), and is the most satiating macronutrient, making any diet easier to sustain.

How should macros change for cutting vs bulking?

For fat loss, keep protein high and trim mostly carbohydrates and some fat. For lean gains, add a modest calorie surplus that is mainly carbohydrate to fuel training. Fat should rarely drop below about 20% of calories.

How accurate is a macro calculator?

It provides a sound starting point, not a fixed prescription. Individual needs vary with activity, training style, and metabolism, so treat the output as a baseline and adjust based on your results over a few weeks.

What happens if I eat too little fat?

Fat should rarely fall below roughly 20% of calories because it underpins hormone production and the absorption of fat-soluble vitamins (A, D, E, and K). Very low-fat diets can harm hormones and recovery.

Do endurance and strength athletes need different macros?

Yes. Endurance athletes can lower protein slightly and raise carbohydrates to fuel long sessions, while strength athletes in a building phase often hold protein high and add carbohydrates around training.

Related guides

Understanding TDEE → What is TDEE? →
Reviewed by the ToolsmithPro editorial team · Last updated June 2026. Every calculation and conversion runs entirely in your browser — your inputs are never uploaded, stored or shared. Formulas and methodology are documented on our about page; spot an error? tell us and we'll fix it.