Macro calculator
Protein and carbohydrate each supply about 4 kcal per gram; fat supplies 9. That is why a high-fat split produces a much smaller number of grams for the same calories, and why fat is so easy to under-count — a tablespoon of oil is 120 kcal and takes up almost no room on a plate.
A starting point, not a prescription. Anyone with a medical condition, or who is pregnant or breastfeeding, should take dietary advice from a doctor or registered dietitian rather than a calculator.
Macros divide a calorie target into protein, carbohydrate and fat. Protein and carbs are 4 kcal per gram, fat is 9. A 2,400 kcal target on a 30/40/30 split is 180 g protein, 240 g carbs and 80 g fat.
How to set your macros
Of the three, only protein has a genuinely evidence-based target — roughly 1.6 to 2.2 grams per kilogram of bodyweight when training, well above what most splits produce by percentage. Carbohydrate and fat divide the remaining calories, and the ratio between them matters far less for body composition than adherence does. That is the honest reading of the research: people lose weight on low-carb and low-fat diets at about the same rate, and the difference is which one they can actually keep to.
Questions
Macronutrients — protein, carbohydrate and fat. They supply 4, 4 and 9 kcal per gram respectively.