How do I calculate my macros?

Decide your daily calories and the percentage for each nutrient, then convert: calories × percentage ÷ 4 for protein and carbs, ÷ 9 for fat. On 2,200 kcal at 30/40/30: protein 165 g, carbs 220 g, fat 73 g.

Why 4 kcal for protein and carbs but 9 for fat?

Those are the Atwater general factors: digested protein and carbohydrate yield about 4 kilocalories per gram and fat about 9. Alcohol, not used here, gives 7. Nutrition labels are built on the same factors.

What macro split should I start with?

One inside all three AMDR ranges — for example 25–30% protein, 25–30% fat and the rest carbs — suits most people. Endurance athletes often raise carbs, strength trainees protein, and low-carb plans shift calories to fat. Adjust from your results over a few weeks.

The Acceptable Macronutrient Distribution Range: the National Academies' range of intake for each energy nutrient, as a share of calories, that is associated with lower risk of chronic disease while providing enough essential nutrients. For adults, protein 10–35%, carbohydrate 45–65% and fat 20–35%.

Should I count macros or just calories?

Calories decide weight change; macros shape what that weight is made of and how full you feel. Hitting a protein target while in a deficit helps keep muscle, which is why many people track protein closely and let carbs and fat float.

Macro Calculator (Protein, Carbs and Fat in Grams)

Protein, carb and fat grams from your calories and percentages, per day and per meal, checked against the National Academies' AMDR ranges.

Inputs

Daily calories(kcal)

1,000 kcal5,000 kcal

Protein %(%)

10 %50 %

Fat %(%)

10 %50 %

Meals a day

Include CalculateEveryday mark

Daily macros

P 150g · C 225g · F 56g

2000 kcal

Protein600 (30%)
Carbs900 (45%)
Fat504 (25%)

Protein: 150 g
Carbs: 225 g
Fat: 56 g
Working, protein: 2,000 × 30% ÷ 4 = 150 g
Working, carbs: 2,000 × 45% ÷ 4 = 225 g
Working, fat: 2,000 × 25% ÷ 9 = 56 g
Per meal (3 a day): P 50g · C 75g · F 19g
Protein vs the AMDR: 30% — inside 10–35%
Carbs vs the AMDR: 45% — inside 45–65%
Fat vs the AMDR: 25% — inside 20–35%

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What each Macro input means

Daily calories: Your daily target: maintenance calories to hold weight, or that minus a deficit to lose. The TDEE and maintenance-calories pages give the starting figure.
Protein %: Share of calories from protein. 25–35% is common when training; the AMDR allows 10–35%. If you think in grams per kilogram instead, the protein-intake page works that way.
Fat %: Share from fat. The AMDR is 20–35%; going much below 20% makes it hard to get enough essential fatty acids.
Meals a day: How many meals or snacks to split the day into. It changes only the per-meal line, not the daily totals.

Macro formula

Protein (g) = calories × protein% ÷ 4 · Fat (g) = calories × fat% ÷ 9 · Carbs (g) = calories × (100 − protein% − fat%) ÷ 4

Macros are the three nutrients that supply calories: protein, carbohydrate and fat. A gram of protein or carbohydrate yields about 4 kcal and a gram of fat about 9 — the Atwater general factors, which food labels also use. So a calorie budget and a percentage split turn straight into grams: take the calories for each nutrient and divide by its factor. You set protein and fat; carbohydrate takes whatever share is left. The National Academies give Acceptable Macronutrient Distribution Ranges for adults — 10–35% of calories from protein, 45–65% from carbohydrate and 20–35% from fat — as the ranges linked with lower chronic-disease risk while still meeting nutrient needs, and the page tells you whether each share sits inside its range. Low-carb or high-protein plans fall outside on purpose; the check simply makes that visible. The per-meal line divides the day evenly, which is a planning convenience, not a rule.

Macro worked example

On 2,000 kcal with 30% protein and 25% fat, carbs get the remaining 45%. Protein: 2,000 × 0.30 = 600 kcal, ÷ 4 = 150 g. Fat: 500 kcal ÷ 9 = 56 g. Carbs: 900 kcal ÷ 4 = 225 g. All three are inside their AMDR ranges, and across three meals that is about 50 g protein, 75 g carbs and 19 g fat each.

More Macro examples

A lower-carb plan of 1,800 kcal with 35% protein and 40% fat leaves 25% for carbs: P 158g · C 113g · F 80g. Protein is at the top of its 10–35% range, carbs are below 45% and fat is above 35%, so the page flags both — a deliberate choice on a low-carb diet, not an error.

Where the Macro calculator can give the wrong answer

If protein and fat add up to more than 100%, there is nothing left for carbohydrate and the page refuses the split.
Grams are rounded to whole numbers, so the three macros can add up to a few calories more or less than the target.
4/4/9 are general factors. Fibre yields less than 4 kcal a gram, and labels in some countries count it at 2, so a high-fibre day has a little less energy than the arithmetic says.
The AMDR applies to healthy adults. Children, pregnancy and medical diets have their own targets, and a clinician's plan overrides these ranges.
Very high protein shares on low calories can leave fat below 20%; keep an eye on the fat line when cutting hard.

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Macro reference table

Acceptable Macronutrient Distribution Ranges, adults
Nutrient	Share of calories	kcal per gram
Protein	10–35%	4
Carbohydrate	45–65%	4
Fat	20–35%	9
Alcohol (not a nutrient target)	—	7

Source: Institute of Medicine, Dietary Reference Intakes for Energy and Macronutrients (2005); USDA Atwater factors

Macro FAQ

: Decide your daily calories and the percentage for each nutrient, then convert: calories × percentage ÷ 4 for protein and carbs, ÷ 9 for fat. On 2,200 kcal at 30/40/30: protein 165 g, carbs 220 g, fat 73 g.
: Those are the Atwater general factors: digested protein and carbohydrate yield about 4 kilocalories per gram and fat about 9. Alcohol, not used here, gives 7. Nutrition labels are built on the same factors.
: One inside all three AMDR ranges — for example 25–30% protein, 25–30% fat and the rest carbs — suits most people. Endurance athletes often raise carbs, strength trainees protein, and low-carb plans shift calories to fat. Adjust from your results over a few weeks.
: The Acceptable Macronutrient Distribution Range: the National Academies' range of intake for each energy nutrient, as a share of calories, that is associated with lower risk of chronic disease while providing enough essential nutrients. For adults, protein 10–35%, carbohydrate 45–65% and fat 20–35%.
: Calories decide weight change; macros shape what that weight is made of and how full you feel. Hitting a protein target while in a deficit helps keep muscle, which is why many people track protein closely and let carbs and fat float.