Cutting Macro Calculator
A high-protein 40/30/30 split that helps protect lean mass while you eat in a calorie deficit — enter your calorie total and get exact protein, carbohydrate and fat gram targets.
Calculate Your Macros
Enter your daily calorie target. Typical ranges: 1,200–2,000 kcal (weight loss), 2,000–3,000 kcal (maintenance), 3,000–5,000+ kcal (athletic or bulking).
Range: 15–100 years. Adult macro ratios aren’t validated for under-19s — add your age and we’ll flag if these targets need a paediatrician’s sign-off.
Moderate exercise most days of the week. Recommended protein: 1.2–1.6 g/kg body weight (ISSN guidelines).
*This calculator is for informational purposes only. Please consult a healthcare professional before making any health decisions. See our medical disclaimer for more information.
Calculations are powered by the Atwater General Factor System, the universally accepted standard for macronutrient caloric conversion (protein: 4 kcal/g, carbohydrate: 4 kcal/g, fat: 9 kcal/g).
Quick Answer
What Are Cutting Macros?
A cutting split is high-protein — commonly 40% protein, 30% carbohydrate and 30% fat — applied to the calorie total you are eating in a deficit. The tool converts those shares into grams using the Atwater factors: protein and carbohydrate at 4 calories per gram, fat at 9. Enter your calorie total above and the exact grams appear.
Why Protein Leads a Cut
On a cut you are eating below maintenance, and a larger protein share is the usual response — a higher protein intake supports lean-mass retention and tends to keep you fuller while calories are low. That is why cutting splits push protein to around 40% rather than the 30% of a balanced day. It is worth being clear about what this page does and does not do: it splits a calorie total into grams, it does not set the deficit. The size of that deficit — how far below maintenance you eat — is decided elsewhere; this tool only arranges whatever total you bring to it.
A Worked Cutting Split
Take a 1,700-calorie cutting day on 40/30/30. Protein is 40% of 1,700, which is 680 calories, and at 4 calories per gram that is 170 grams. Carbohydrate is 30%, or 510 calories, again at 4 calories per gram — 128 grams. Fat is the last 30%, another 510 calories, but at 9 calories per gram it comes to about 57 grams. So 1,700 cutting calories on this split is 170 g protein, 128 g carbohydrate and 57 g fat. Enter your own total above to see it worked for your number, and refine the protein figure against body weight with the Protein Intake Calculator.
Where Your Cutting Calories Come From
Because this page splits but does not set your total, you need that calorie number from somewhere first. Work it out with the Calorie Deficit Calculator, which takes maintenance and subtracts the deficit you choose, then bring the result here to split into grams. Or start from the Macro Calculator to compare this cutting split against other ratios on the same total. These figures are general estimates for healthy adults, not medical advice.
Gram targets use the Atwater general factor system — protein and carbohydrate at 4 calories per gram, fat at 9 — the same standard published in the Dietary Reference Intakes for Macronutrients (National Academies of Sciences, 2005). The split is arithmetic, not a personalised prescription; individual needs vary, so check with a clinician or registered dietitian before making changes if you manage a medical condition.
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