Macro Split Grams Calculator

📖 Overview

Use this calculator to translate nutrition percentages into actionable daily macro grams.

Use these default and higher-pressure example inputs to explore how sensitive this calculator is before using your real numbers.

This converts calorie and macro percentage targets into grams for protein, fat, and carbohydrates.

The Formula

Protein (g) = Calories × Protein% ÷ 400 | Fat (g) = Calories × Fat% ÷ 900 | Carbs (g) = Calories × Carb% ÷ 400

Protein & Carbs	4 kcal per gram — divide calorie allocation by 4
Fat	9 kcal per gram — divide calorie allocation by 9

💡Protein is 4 kcal/g, carbohydrates are 4 kcal/g, and fat is 9 kcal/g. This is why fat grams are lower despite the same calorie allocation.

Goal	Protein %	Fat %	Carb %	Notes
General health	20%	30%	50%	Balanced macros
Fat loss	30%	30%	40%	Higher protein for satiety
Muscle gain	25%	25%	50%	Carb-supported training
Keto	20%	75%	5%	Very low carbohydrate
Endurance athlete	15%	25%	60%	Carb-heavy for fuel

Use this tool when you need a fast decision during active planning or execution.
Use this before committing money, time, or tradeoffs that are hard to reverse.
Use this to compare options using the same assumptions across scenarios.

Results can be misleading if key inputs are missing, stale, or unrealistic.
Very small or very large values may amplify rounding effects and interpretation risk.
If assumptions change mid-decision, recalculate before acting.

💡 Ensure macro percentages sum close to 100.

💡 Recalculate after calorie target changes.

💡 Run a best-case, base-case, and worst-case scenario before deciding.

💡 Use recent real values, not ideal assumptions, for better accuracy.

❓ Why are fat grams lower for same calories?

Fat is 9 kcal per gram while protein and carbs are 4.

❓ Can I use non-100% macro totals?

Yes, but remaining calories become unassigned in this estimate.