Macro Split Calculator

A macro split takes the calories you plan to eat and divides them into grams of protein, carbohydrate, and fat. It's a planning tool: once you know a calorie target, the split tells you roughly how much of each nutrient to aim for.

There's no single "correct" split. A balanced ratio works well for general health; a higher-protein split supports building or keeping muscle; lower-carb and higher-carb ratios suit particular diets or training demands. The presets here give you a sensible starting point for each.

The important nuance: the calorie-to-gram maths is exact, but the percentages are a convention, not a prescription. Use the result as a target to experiment with, and adjust based on your goals, how you feel, and how your body responds.

Formula. For each macro: grams = (its percentage × your calories) ÷ its energy value, using the Atwater factors of 4 kcal/g for protein and carbs and 9 kcal/g for fat.

Presets. Balanced (30/40/30), High protein (40/35/25), Low carb (40/20/40), and High carb (25/55/20), given as protein/carbs/fat percentages. For context, the IOM's Acceptable Macronutrient Distribution Ranges are protein 10–35%, carbs 45–65%, and fat 20–35% — some presets (such as low-carb) intentionally sit outside those ranges.

Confidence. We label this moderate confidence: the arithmetic is exact, but the preset ratios are conventions rather than a single guideline, so treat the split as a starting point to personalise.