Macro Calculator: Protein, Carbs and Fat

Macro Calculator

Get your daily protein, carbohydrate and fat in grams for losing fat, maintaining or building muscle. Protein is set per kilogram of body weight, fat by your diet style, and carbs fill the rest, then everything is split across your meals.

By the FitStack team. Last updated October 18, 2026. Formulas and sources are listed on this page.

How the macros are calculated

Calories come from your TDEE (Mifflin-St Jeor and your activity level) adjusted for your goal: −20% to lose fat, −10% for recomposition, +10% to gain. Or enter your own calorie target.⁸ Then the calories are divided in three steps.

1. Protein, per kg of body weight

Goal	Protein
Lose fat	2 g/kg
Recomp	2 g/kg
Build muscle	1.8 g/kg
Maintain	1.6 g/kg

A meta-analysis of 49 trials found gains in muscle from resistance training level off around 1.6 g/kg a day, with an upper confidence limit of 2.2 g/kg.² Dieting raises needs, so fat-loss targets sit higher.³^,⁴ Protein is capped at 35% of calories, the top of the Institute of Medicine's acceptable range.¹ At a BMI of 30 or more, protein is based on adjusted body weight (the weight at BMI 25 plus 40% of the difference) because protein needs follow lean mass, not fat mass.⁷

2. Fat, by diet style

Balanced: Fat at 30% of calories, carbs fill the rest. Suits most people.
Lower carb: Carbs held at 20% of calories, fat fills the rest.
Keto: Carbs held at 25 g a day, fat fills the rest.
Endurance: Fat at 20% of calories so carbs can fuel high training volume.

Fat never drops below 20% of calories, the bottom of the acceptable range, because dietary fat supports hormone production and the absorption of fat-soluble vitamins.¹ Keto keeps carbohydrate at 25 g, below the roughly 50 g a day at which ketosis usually begins.⁶

3. Carbohydrate fills the rest

Carbs (g) = (calories − protein g × 4 − fat g × 9) ÷ 4

Endurance athletes training about an hour a day generally need 5 to 7 g of carbs per kg; the calculator flags it if your calories can't cover that on the endurance setting.⁵ Fiber is set at 14 g per 1,000 kcal.¹

Worked example

A 34-year-old woman, 168 cm and 72 kg, moderately active, losing fat on a balanced diet with four meals:

Calories: TDEE 2,230 × 0.8 = 1,780 kcal Protein: 2.0 × 72 = 145 g (580 kcal) Fat: 30% × 1,780 ÷ 9 = 59 g (534 kcal) Carbs: (1,780 − 580 − 534) ÷ 4 = 167 g Per meal: about 36 g protein, 42 g carbs, 15 g fat

Getting the most from your numbers

Hit calories and protein first. Carbs and fat can vary by 10 to 20 g a day without changing results.
Spread protein across your meals; about 0.4 g/kg per meal suits muscle building.
Recheck after every 4 to 5 kg of weight change, or use the TDEE calculator to see how your maintenance has moved.

Want a closer look at protein alone? The protein calculator adjusts for age and training, and the calorie deficit calculator lets you choose a weekly pace of loss.

Frequently asked questions

What are the best macros for fat loss?

High protein, enough fat and the rest from carbohydrate. In practice that is about 1.6 to 2.2 g of protein per kg of body weight, at least 20% of calories from fat, and carbs filling the remainder. Within that, the split that you can stick to matters more than the exact percentages.

Do macros matter if my calories are right?

Calories determine how much weight you lose or gain. Macros, mainly protein, influence what that weight is: enough protein with strength training means more of the loss comes from fat and more of any gain is muscle. Carbs and fat matter more for training performance and how full you feel than for fat loss itself.

Should I count net carbs or total carbs?

Total carbs for a standard diet. Net carbs (total minus fiber, and sometimes sugar alcohols) are mainly used on keto, where staying under about 50 g a day is the goal. Labels outside the US often already list carbohydrate without fiber, so check which one you're reading.

How can I hit my macros without weighing every gram?

Track protein and calories closely and let carbs and fat land roughly where they land. Build each meal around a palm-to-hand-sized portion of protein, add a fist of carbs and a thumb of fat, and weigh food for a week or two to calibrate your eye.

Is a 40/30/30 split better?

Fixed percentage splits are easy to remember but give odd protein numbers at the extremes: too little for a small, active person on low calories and more than needed for a large person on high calories. Setting protein per kg of body weight and then dividing the rest avoids that.