Macro Split Calculator
Turn a daily calorie number into protein, fat and carb grams — set by goal, inside published evidence bands. Protein is fixed first, fat second, and carbs take whatever calories remain.
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The math, shown
Order of operations: protein is set first in g/kg from the 1.6–2.2 g/kg evidence band (Morton 2018) — higher while dieting (Helms 2014). Fat is set second as a percentage of calories, inside the 15–30% range used in contest-prep guidance (Helms 2014). Carbs are not assigned — they are whatever calories remain, because carbs are the flexible fuel lever.
Conversion: protein and carbs count 4 kcal per gram, fat 9 kcal per gram — the Atwater general factors used in food-labelling worldwide (FAO 2003).
Macro splits matter far less than total calories and protein. Two splits with the same calories and protein produce similar results — pick the one whose meals you will actually eat.
These are population formulas — a starting point, not a prescription. Your training history, sleep, stress and cycle shift the real answer. That is what the 9-axis Body Scan measures.
Sources
- Morton RW, Murphy KT, McKellar SR, et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training–induced gains in muscle mass and strength in healthy adults. Br J Sports Med. 2018;52(6):376–384.
- Helms ER, Aragon AA, Fitschen PJ. Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation. J Int Soc Sports Nutr. 2014;11:20.
- Food and Agriculture Organization of the United Nations. Food energy — methods of analysis and conversion factors. FAO Food and Nutrition Paper 77. Rome: FAO; 2003.
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These numbers are the first 10% of a plan.
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