How to count protein, fats and carbs: example

How many kcal are in a gram of each macro

Conversion factors from Annex XIV of EU Regulation 1169/2011
Nutrient	kcal per gram
Protein	4
Fat	9
Carbohydrate (excluding polyols)	4
Fibre	2
Alcohol (ethanol)	7

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Manufacturers use these factors to work out the energy on the label. The label also counts fibre and polyols (2.4 kcal/g), so your sum of the three macros may not match the pack's kcal figure exactly. A small gap is normal.

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The order: calories, protein, fats, carbs

Calories: your daily target, from a calculator or from watching your weight.
Protein: grams per kilogram of body weight. The ISSN position stand gives 1.4-2.0 g/kg a day for most people who exercise, and says resistance-trained people in a calorie deficit may need 2.3-3.1 g/kg.
Fats: a share of calories. Reviews for lifters give 15-30% of calories (contest prep, Helms et al.), 20-30% (fat loss phase, Ruiz-Castellano et al.) or 0.5-1.5 g/kg (off-season, Iraki et al.).
The rest: calories minus protein and fats, divided by 4, is your carbs.

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Protein goes first because studies give it in grams per kilogram of body weight, whatever your calories are. Carbs go last because in Helms et al. and Iraki et al. they fill the remaining calories. When you change your calorie target, you mostly change your carbs.

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Example: splitting 2,600 kcal

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The 2,600 kcal split from the example (80 kg, 2.0 g protein per kg)
Macro	Grams	kcal	Share
Protein	160 g	640	25%
Fats	72 g	648	25%
Carbs	328 g	1,312	50%

How to read a food label

In the EU, energy and nutrients are given per 100 g or per 100 ml. Look for the nutrition table; Polish packs usually head it "Wartość odżywcza w 100 g". A manufacturer may add per-portion values, but must then state the portion size next to them.

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Find the energy line and take the kcal figure (the same value in kJ sits next to it).
Copy protein, fat and carbohydrate. The label lists them in a different order: fat, carbohydrate, fibre, protein, salt.
Do not add "of which sugars" or "of which saturates": they are part of the figure above, not separate nutrients.
Weigh your portion and multiply each value by the grams divided by 100.

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Weighing: raw or cooked

Cooking changes how much water the food holds: per USDA, 100 g of raw rice has 11.6 g of water and cooked rice 68.4 g; raw chicken breast 73.9 g and roasted 65.3 g. So 100 g before and after cooking are different numbers. Weigh food in the same state as the values you log.

Values per 100 g from USDA FoodData Central
Food	kcal	Protein
Long-grain white rice, raw	365	7.1 g
Long-grain white rice, cooked	130	2.7 g
Chicken breast, raw	120	22.5 g
Chicken breast, roasted	165	31.0 g

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How an app does the arithmetic for you

An app runs the same sums: it multiplies grams by per-100 g values, adds up your meals and takes the total off your daily target. It works from the grams you give it. When you weigh food, two things are your call: the weight of the portion and whether you log it raw or cooked.

How CalXd does it

CalXd calculates your daily calorie and macro targets from your profile and goal; you can also set the calorie target yourself. It always shows macros in this order: calories, protein, fats, carbs.

Log a meal by photo, voice, text or barcode. Type, for example, "200 g chicken breast with 100 g rice" and CalXd estimates the values; scan a barcode and it looks the product up in Open Food Facts, and you pick the portion, including your own grams. AI results are estimates, marked with "≈": correct the portion with one tap, or edit the numbers by hand.

Questions

How do I work out my macros on a cut?

The same way as in the example: calorie target first, then protein from body weight, then fats, and carbs from what is left. For a cut, the ISSN position stand says resistance-trained people may need 2.3-3.1 g protein per kg, and Ruiz-Castellano et al. give 20-30% of calories from fats.

How much protein a day if I lift?

The ISSN position stand gives 1.4-2.0 g per kilogram of body weight a day for most people who exercise. In the Morton et al. meta-analysis, gains in fat-free mass levelled off at about 1.62 g/kg, and the authors suggest about 2.2 g/kg for those who want to maximise them.

Do I count the sugars on the label separately?

No. "Of which sugars" is part of the carbohydrate figure above it, just as "of which saturates" is part of fat. Adding them again inflates your total.

Should fibre count towards carbs?

On EU labels fibre is its own line under carbohydrate, with its own factor of 2 kcal/g. Copy the label's carbohydrate figure as it is, without adding or taking off fibre. USDA data works differently: "Carbohydrate, by difference" is 100 g minus water, protein, fat and ash, so it includes fibre (raw rice: 80.0 g, of which 1.3 g fibre). Those figures are not like-for-like with an EU label.

How do you count protein, fats and carbs?