What split does this calculator use?

A fixed 30% protein / 40% carbohydrate / 30% fat split, applied to whatever calorie target you enter. It’s a balanced, protein-forward starting point often used for general fitness and body-composition goals. Individual needs vary, so treat the gram targets as a baseline to adjust, not a prescription.

Where do the 4, 4, and 9 come from?

They’re the Atwater factors — the standard average energy contents of the macronutrients. Protein and carbohydrate each provide about 4 kcal per gram, while fat provides about 9 kcal per gram, and nutrition labels are built on the same values. Alcohol, which this calculator doesn’t cover, provides about 7 kcal per gram.

How much protein do I actually need?

The adult RDA is 0.8 g per kilogram of body weight per day, which is a minimum to prevent deficiency rather than an optimum for training. Sports-nutrition guidance commonly recommends roughly 1.6–2.2 g per kg for people building or preserving muscle. At a 2,000 kcal target, this tool’s 150 g of protein works out to about 1.9 g per kg for an 80 kg person. This is general guidance only, not medical advice.

Where do I get my daily calorie target?

Start from an estimate of your maintenance calories — a BMR/TDEE calculator gives you that from your weight, height, age, and activity level — then adjust it down for fat loss or up for muscle gain. This tool deliberately does one job: converting the target you choose into daily gram goals.

Why don’t the grams add back up to my exact calories?

Each gram figure is rounded to the nearest whole gram, so the implied calories can drift a few kcal from your target — in the 2,000 kcal example the rounded grams imply 2,003 kcal. Differences this small are meaningless in practice; the rounding on food labels is larger.

No. The split is calculated entirely in your browser, and the calorie figure you enter never leaves your device.

Macro Calculator

Split your daily calories into protein, carbs and fat grams.

Runs in your browser — files never leave your device

Daily calorieskcal

Protein (30%)

150 g

Carbs (40%)

200 g

Fat (30%)

67 g

How it works

This calculator turns a daily calorie target into daily gram targets for the three macronutrients: protein, carbohydrate, and fat. It combines a fixed balanced split — 30% of calories from protein, 40% from carbohydrate, and 30% from fat — with the standard Atwater energy values: protein and carbohydrate provide about 4 kcal per gram, and fat provides about 9 kcal per gram.

The math is three one-line formulas. Protein grams = calories × 0.30 ÷ 4. Carbohydrate grams = calories × 0.40 ÷ 4. Fat grams = calories × 0.30 ÷ 9. Each result is rounded to the nearest whole gram, which is why the displayed grams can re-add to a few kcal above or below your target.

Worked example with a 2,000 kcal target: protein gets 30% of 2,000 = 600 kcal, and 600 ÷ 4 = 150 g. Carbohydrate gets 40% = 800 kcal, and 800 ÷ 4 = 200 g. Fat gets 30% = 600 kcal, and 600 ÷ 9 = 66.67, which rounds to 67 g. Re-adding the rounded grams (150 × 4 + 200 × 4 + 67 × 9) gives 2,003 kcal — the 3 kcal difference is rounding, not an error.

For context, US dietary guidance (the Acceptable Macronutrient Distribution Ranges) puts protein at 10–35%, carbohydrate at 45–65%, and fat at 20–35% of calories, so this tool’s 30/40/30 split is protein-forward and slightly lower in carbohydrate than that midpoint. The right ratio for you depends on training, goals, food preferences, and health conditions — and for most people the calorie target itself matters more than the exact split. This tool offers general guidance only and is not medical advice; consult a registered dietitian for a personalized plan, especially if you have diabetes, kidney disease, or are pregnant.

Frequently asked questions

What split does this calculator use?: A fixed 30% protein / 40% carbohydrate / 30% fat split, applied to whatever calorie target you enter. It’s a balanced, protein-forward starting point often used for general fitness and body-composition goals. Individual needs vary, so treat the gram targets as a baseline to adjust, not a prescription.
Where do the 4, 4, and 9 come from?: They’re the Atwater factors — the standard average energy contents of the macronutrients. Protein and carbohydrate each provide about 4 kcal per gram, while fat provides about 9 kcal per gram, and nutrition labels are built on the same values. Alcohol, which this calculator doesn’t cover, provides about 7 kcal per gram.
How much protein do I actually need?: The adult RDA is 0.8 g per kilogram of body weight per day, which is a minimum to prevent deficiency rather than an optimum for training. Sports-nutrition guidance commonly recommends roughly 1.6–2.2 g per kg for people building or preserving muscle. At a 2,000 kcal target, this tool’s 150 g of protein works out to about 1.9 g per kg for an 80 kg person. This is general guidance only, not medical advice.
Where do I get my daily calorie target?: Start from an estimate of your maintenance calories — a BMR/TDEE calculator gives you that from your weight, height, age, and activity level — then adjust it down for fat loss or up for muscle gain. This tool deliberately does one job: converting the target you choose into daily gram goals.
Why don’t the grams add back up to my exact calories?: Each gram figure is rounded to the nearest whole gram, so the implied calories can drift a few kcal from your target — in the 2,000 kcal example the rounded grams imply 2,003 kcal. Differences this small are meaningless in practice; the rounding on food labels is larger.
Is my data uploaded?: No. The split is calculated entirely in your browser, and the calorie figure you enter never leaves your device.

Macro Calculator

How it works

Frequently asked questions

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