Split calories into protein, carbs and fat

Macro calculator

Calculate your daily protein, carbohydrate, and fat targets in grams from a total calorie target and macro split.

Formula

grams = (daily calories × macro %) ÷ calories per gram (protein & carbs = 4 kcal/g, fat = 9 kcal/g)

Assumptions

• Fat is whatever percentage remains after protein and carbs — if protein % and carb % together exceed 100%, fat is treated as 0%.
• The default 30/40/30 split is one common starting point, not a guideline figure. The Institute of Medicine's acceptable ranges are 10-35% protein, 45-65% carbohydrate and 20-35% fat, so a 40% carb target sits just below that band — deliberate for some goals, worth knowing for others.
• This is informational only, not medical or nutritional advice — individual needs vary by activity level, goals, and health conditions.

Frequently asked questions

What macro split should I use?
A common general starting point is roughly 30% protein, 40% carbs, and 30% fat, but this varies widely by goal (e.g. higher protein for muscle building, lower carb for other approaches) — adjust the sliders to match your own plan or a nutritionist's recommendation.

Why are protein and carbs calculated differently from fat?
Protein and carbohydrates each provide about 4 calories per gram, while fat provides about 9 calories per gram — this is a basic nutritional science constant used to convert a calorie budget into grams.

Sources

• NASEM — Dietary Reference Intakes: macronutrient ranges