Free calculator

Macro Calculator

Written by the GymStreak coaching teamUpdated 29 September 2026

Sex

Units

Age (years)

Weight (kg)

Height (cm)

Activity level

Goal

The short answer

To work out your macros, estimate the calories you burn per day (TDEE), adjust for your goal, set protein by body weight, set fat as a share of calories and give the rest to carbs. For example, an 80 kg man who trains 3 to 5 times a week and wants to lose fat gets about 2,260 calories: 160 g of protein, 63 g of fat and 263 g of carbs. Protein and carbs have about 4 calories per gram and fat about 9.

01 / How it works

How the macro calculator works

Macronutrients, or macros, are the three nutrients that supply calories: protein, carbohydrate and fat. Your calorie total decides whether you lose, keep or gain weight; how those calories split between the macros affects how well you keep or build muscle, how you train and how full you feel.

The calculator works in four steps. It estimates your resting burn (BMR) with the Mifflin-St Jeor equation, multiplies it by an activity factor to get your total daily burn (TDEE), then subtracts 500 calories to lose fat or adds 500 to build muscle. Finally it splits that target: protein from your body weight (2.0 g per kg when losing fat, 1.6 g per kg otherwise), fat as a fixed share of calories (25% when losing or gaining, 30% at maintenance) and carbs from whatever calories are left.

Carbs are never allowed to go below zero. At very low calorie targets, where protein and fat alone would use up every calorie, the calculator sets carbs to zero, trims fat to fit and tells you. Every result shows grams, calories and the share of your total for each macro, so you can compare it with the ranges in the tables below.

02 / Formula

The macro formulas

Step 1 and 2: BMR and TDEE

Men:   BMR = 10 × weight + 6.25 × height − 5 × age + 5
Women: BMR = 10 × weight + 6.25 × height − 5 × age − 161
TDEE  = BMR × activity factor (1.2 to 1.9)

weight in kg, height in cm, age in years
activity factors are conventional estimates; see the table below

Source: Mifflin MD, St Jeor ST, et al. Am J Clin Nutr. 1990;51(2):241-247.

Step 3: calorie target

Lose fat:     target = TDEE − 500
Maintain:     target = TDEE
Build muscle: target = TDEE + 500

A 500-calorie daily change gives roughly 0.5 kg (1 lb) a week at first. Progress slows over time as your body adapts, so recalculate as your weight changes.

Source: Hall KD, et al. Quantification of the effect of energy imbalance on bodyweight. Lancet. 2011;378(9793):826-837.

Step 4: macro split

Protein (g) = weight in kg × 2.0 (lose fat) or × 1.6 (maintain, build muscle)
Fat (g)     = target × 25% ÷ 9 (lose fat, build muscle) or × 30% ÷ 9 (maintain)
Carbs (g)   = (target − protein g × 4 − fat g × 9) ÷ 4, never below 0

protein and carbohydrate ≈ 4 kcal per gram; fat ≈ 9 kcal per gram

The protein figures sit inside the 1.4 to 2.0 g/kg a day that the International Society of Sports Nutrition recommends for people who exercise. 1.6 g/kg matches the point in a large meta-analysis beyond which extra protein added no further muscle gain on average; 2.0 g/kg, the top of the ISSN range, is used in a deficit to help protect muscle. The fat shares sit inside the 20 to 35% range set by the US Institute of Medicine.

Source: Jäger R, et al. ISSN position stand: protein and exercise. J Int Soc Sports Nutr. 2017;14:20.

03 / Worked example

Worked examples

Losing fat: a 30-year-old man, 180 cm, 80 kg, moderate activity

He lifts four days a week and has a desk job, so he picks moderate (×1.55) and lose fat.

1BMR = 10 × 80 + 6.25 × 180 − 5 × 30 + 5 = 1,780 kcal
2TDEE = 1,780 × 1.55 = 2,759 kcal · Target = 2,759 − 500 = 2,259 kcal
3Protein = 80 × 2.0 = 160 g = 640 kcal (28%)
4Fat = 2,259 × 0.25 ÷ 9 ≈ 63 g = 567 kcal (25%)
5Carbs = (2,259 − 640 − 567) ÷ 4 = 1,052 ÷ 4 = 263 g (47%)

About 2,260 calories: 160 g protein, 63 g fat, 263 g carbs. The same numbers as the TDEE calculator gives him, because both use the same rules when cutting.

Maintaining: a 35-year-old woman, 165 cm, 65 kg, light activity

She walks most days and does two workouts a week, so she picks light (×1.375) and maintain.

1BMR = 10 × 65 + 6.25 × 165 − 5 × 35 − 161 ≈ 1,345 kcal
2TDEE = 1,345.25 × 1.375 ≈ 1,850 kcal = target
3Protein = 65 × 1.6 = 104 g = 416 kcal (22%)
4Fat = 1,850 × 0.30 ÷ 9 ≈ 62 g = 558 kcal (30%)
5Carbs = (1,850 − 416 − 558) ÷ 4 = 876 ÷ 4 = 219 g (47%)

About 1,850 calories: 104 g protein, 62 g fat, 219 g carbs.

Building muscle: a 25-year-old man, 175 cm, 70 kg, active

He trains hard six days a week, so he picks active (×1.725) and build muscle.

1BMR = 10 × 70 + 6.25 × 175 − 5 × 25 + 5 ≈ 1,674 kcal
2TDEE = 1,673.75 × 1.725 ≈ 2,887 kcal · Target = 2,887 + 500 = 3,387 kcal
3Protein = 70 × 1.6 = 112 g = 448 kcal (13%)
4Fat = 3,387 × 0.25 ÷ 9 ≈ 94 g = 846 kcal (25%)
5Carbs = (3,387 − 448 − 846) ÷ 4 = 2,093 ÷ 4 ≈ 523 g (62%)

About 3,390 calories: 112 g protein, 94 g fat, 523 g carbs. After a few weeks he should check the scale: if he is gaining faster than he wants, he can trim the surplus by 100 to 200 calories.

04 / Reference

Macro charts and tables

How the calculator splits macros by goal

Goal	Calories	Protein	Fat	Carbs	80 kg man, moderate (TDEE 2,759)
Lose fat	TDEE − 500	2.0 g/kg	25% of calories	The rest	2,259 kcal · 160 g P · 63 g F · 263 g C
Maintain	TDEE	1.6 g/kg	30% of calories	The rest	2,759 kcal · 128 g P · 92 g F · 355 g C
Build muscle	TDEE + 500	1.6 g/kg	25% of calories	The rest	3,259 kcal · 128 g P · 91 g F · 482 g C

Protein is set per kilogram rather than as a percentage, so it stays steady when calories change and carbs take up most of the difference.

Recommended ranges to check your result against

Nutrient	Range	Who says so
Protein	10–35% of calories	US Institute of Medicine (AMDR), all adults
Protein	1.4–2.0 g per kg a day	ISSN, people who exercise
Fat	20–35% of calories	US Institute of Medicine (AMDR)
Carbohydrate	45–65% of calories	US Institute of Medicine (AMDR)

The Institute of Medicine ranges are for the general adult population, so a sports-focused split can fall a little outside them, for example protein above 35% of calories on a low-calorie diet. If you have a medical condition, check your targets with a dietitian.

Source: Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. National Academies Press; 2005.

Activity factors

Activity level	Typical week	Factor
Sedentary	Desk job, little or no exercise	1.2
Light	Exercise 1–3 days a week	1.375
Moderate	Exercise 3–5 days a week	1.55
Active	Hard exercise 6–7 days a week	1.725
Very active	Hard daily training plus a physical job	1.9

Conventional estimates, not measured values. If you are unsure between two levels, pick the lower one.

Calories per gram

Macronutrient	kcal per gram	Main foods
Protein	4	Meat, fish, eggs, dairy, tofu, beans, lentils
Carbohydrate	4	Rice, oats, bread, pasta, potatoes, fruit
Fat	9	Oils, butter, nuts, seeds, avocado, cheese

05 / Training

How to use your macros

Hit calories and protein first. They matter most for body composition. Being roughly on target for fat and carbs is enough for most people; nobody needs to hit them to the gram.
Spread protein across the day. Three or four meals with a good protein source each is easier than one huge serving. How much protein should you eat to lose weight? and how to create meal plans for a high-protein diet have practical ideas.
Train to give the protein a job. Resistance training is what turns protein into muscle. Build sessions around barbell squats, the barbell bench press, lat pulldowns and the dumbbell Romanian deadlift.
Check progress after two to three weeks. If your average weight is not moving the way you want, change calories by 100 to 200 a day, mostly from carbs or fat, and keep protein where it is.
Deciding between cutting and bulking? Read cut versus bulk: which should you do first? and how many calories to eat when bulking.

06 / Limitations

Limitations and safety

The calorie target is only as good as the BMR equation and your activity level. Mifflin-St Jeor predicts resting burn within 10% for more people than the other common equations, but not for everyone, and the activity factor adds more uncertainty. Your weight trend over a few weeks is the real test.

Protein is set per kilogram of total body weight. If you carry a lot of body fat, that can give a very high protein figure; some coaches base it on a goal weight instead. The calculator shows a note when your BMI is 30 or more.

Calorie targets under about 1,200 a day are not a good idea without supervision. If you get one, or you have diabetes, kidney disease, a history of disordered eating or are pregnant, talk to a doctor or registered dietitian before changing how you eat.

This calculator gives an estimate for general fitness education. It is not medical advice and does not diagnose anything. If you have a health condition, are pregnant, or are new to hard exercise, check with a doctor first.

07 / FAQ

Frequently asked questions

How do I calculate my macros?

Work out your daily calorie burn (TDEE), subtract about 500 calories to lose fat or add about 500 to gain, then set protein at about 1.6 to 2.0 g per kg of body weight, fat at 25 to 30% of calories, and fill the remaining calories with carbs. Divide protein and carb calories by 4 and fat calories by 9 to get grams.

How much protein do I need per day?

For people who exercise, the International Society of Sports Nutrition recommends 1.4 to 2.0 g of protein per kg of body weight a day. This calculator uses 1.6 g/kg to maintain or build muscle and 2.0 g/kg when losing fat. For an 80 kg person that is 128 g or 160 g a day.

What is the best macro split for fat loss?

There is no single best split; the calorie deficit drives fat loss. What matters most is keeping protein high, around 2.0 g per kg, and lifting weights so you keep muscle. This calculator uses 2.0 g/kg protein, 25% of calories from fat and the rest from carbs, which for an 80 kg man comes to about 28% protein, 25% fat and 47% carbs.

What macros should I eat to build muscle?

Eat slightly more calories than you burn, get about 1.6 g of protein per kg of body weight, and keep fat around 25% of calories so there is plenty left for carbs to fuel training. A large meta-analysis found that, on average, protein above about 1.6 g/kg a day added no further muscle gain.

Is fibre a macronutrient?

Fibre is a type of carbohydrate, so in this calculator it is counted inside your carb total rather than as a separate macro. It still matters for digestion and fullness, which is why whole grains, fruit, vegetables, beans and lentils are good carb sources.

How many calories are in a gram of protein, carbs and fat?

Protein and carbohydrate each provide about 4 calories per gram, and fat about 9 calories per gram. So 100 g of protein is about 400 calories, and 50 g of fat is about 450.

Why is protein set in grams per kg instead of a percentage?

Your protein needs depend on your body size, not on how many calories you eat. Setting it per kilogram keeps it steady whether you are cutting or bulking, while carbs and fat move with your calorie target.

Can my carbs come out negative?

No. Carbs are whatever calories remain after protein and fat, and the calculator never lets that fall below zero. If your target is so low that protein and fat use it all, it sets carbs to zero, reduces fat to fit and warns you; a target that low usually needs professional advice.

Sources

From the blog

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