Macro
calculator

Protein, carbs, and fat from your TDEE. Protein set per pound of bodyweight the way the ISSN research supports — not a fixed percentage — plus a fibre target most calculators leave off. Imperial or metric.

How the math works

Macros come from your calorie budget in a fixed order: set protein first, set fat second, and let carbohydrate take whatever calories are left. Protein and carbohydrate carry 4 kcal/g; fat carries 9 kcal/g (Atwater factors, USDA DRI).

The calorie budget itself is your TDEE adjusted for the goal. TDEE here uses Mifflin-St Jeor BMR (Mifflin & St Jeor, 1990) times an activity multiplier — the same engine as our TDEE calculator.

Setting protein in grams per pound is the part most calculators skip. The ISSN position stand puts trained lifters at 1.6–2.2 g/kg — about 0.73–1.0 g/lb (Jäger et al., 2017). The default here is 1.0 g/lb, the top of that band; drop it if you're bulking, keep it high on a cut.

Worked example

A 30-year-old, 5'10" (178 cm), 180 lb (82 kg) male on a cut. His TDEE is 2,770 kcal, so a 500 kcal deficit sets the budget at 2,270 kcal. Protein at 1.0 g/lb of bodyweight — about 2.2 g/kg — with fat at 25% of calories:

• Protein: 180 g × 4 = 720 kcal (180 lb × 1.0 g/lb; 82 kg × 2.2 g/kg)
• Fat (25%): 568 kcal / 9 = 63 g
• Carbohydrate (remainder): (2,270 − 720 − 568) / 4 = 246 g
• Fibre target: 14 × 2,270 / 1,000 = 32 g

That's 180 g protein, 246 g carbs, 63 g fat — which happens to be 32% protein at this calorie level, even though nobody set a "32% protein" target. The grams drove the percentage, not the other way round.

When this calculator is wrong

Most calorie targets put protein too low, because they set it as a percentage of intake instead of grams per pound of bodyweight. At 1 g per pound, a 180 lb lifter eating 2,500 kcal is at 29% protein — fine. The same 180 g on a 2,000 kcal cut is 36% protein — also fine, even though it breaks the usual "30% protein" convention. The grams are what preserve muscle in a deficit (Helms et al., 2014); the percentage is just an artefact of the calorie level.

• The percentage counter-case is high-calorie bulks. Above roughly 4,000 kcal, the gram target is easily hit at well under 30% of calories, and the percentage falls on its own. Don't force it back up by swapping carbs or fat for protein — past about 1.8 g/kg there's no added muscle in most people (Morton et al., 2018).
• Lean-mass anchoring needs a real body fat number. Anchoring protein to lean mass is more precise for very lean or very heavy people, but only if the body fat % is measured (DEXA, calipers), not eyeballed. A bad body fat input propagates straight into the protein target.
• The calorie budget inherits TDEE's error. The activity multiplier can overestimate real-world expenditure by 5–15% for desk-job populations (Westerterp, 2017). If the scale isn't moving as expected, the calorie number is the input to re-check first — not the macro ratio.

What to do with the result

Hit protein and calories first; treat the carb and fat split as flexible. Protein and total calories drive body-composition change — the exact carb-to-fat ratio matters far less, so long as fat stays high enough for you to function (most people do fine at 20–30% of calories).

Then calibrate. Track intake and weight for two weeks. If weight is moving at the rate the goal implies (about 1 lb / 0.45 kg per week on the −500 cut), the number is right. If not, adjust calories by 100–200 kcal per week and recompute — keep protein grams fixed and let carbs absorb the change. Recompute macros whenever your bodyweight moves more than about 10 lb (4.5 kg).

Common questions

How do I calculate my macros?

Start from your calorie target (TDEE adjusted for your goal). Set protein at 0.73–1.0 g/lb of bodyweight, set fat at 20–30% of calories, and fill the rest with carbohydrate. Convert grams to calories with 4 kcal/g for protein and carbs, 9 kcal/g for fat.

What's a good macro split for weight loss?

On a cut, keep protein high — 1.0 g/lb of bodyweight or more — to preserve muscle in the deficit (Helms et al., 2014). Fat and carbs split the remaining calories to preference. For the reference subject on a 2,270 kcal cut that works out to roughly 180 g protein, 246 g carbs, 63 g fat, but the protein target is the part that's non-negotiable.

Should I set macros by percentage or by grams?

By grams, at least for protein. A percentage target gives you different protein grams every time your calories change, which is backwards — your protein need is tied to your bodyweight, not to how many calories you happen to be eating that week. Set the grams; let the percentage fall where it falls.

How much protein do I actually need?

The RDA of 0.8 g/kg prevents deficiency in sedentary adults. Anyone training should use the ISSN band of 1.4–2.2 g/kg (about 0.64–1.0 g/lb). During a calorie deficit, needs rise to 2.3–3.1 g/kg of lean mass to hold onto muscle (Helms et al., 2014).

Is fibre a macronutrient?

Not an energy macro — its calories are already counted inside the carbohydrate total, which is why macro calculators usually omit it. It's still worth a target: the IOM/USDA reference intake is 14 g per 1,000 kcal, roughly 25 g/day for women and 38 g/day for men.

Do I need to hit my macros exactly every day?

No. Protein and total calories are what matter; aim to land close on those. The carb-and-fat split can move day to day, and weekly averages matter more than any single day. Precision to the gram buys very little.