Formula
Protein g = calories × protein% ÷ 4Carbs g = calories × carb% ÷ 4Fat g = calories × fat% ÷ 9 How it works
Macronutrients are the three nutrients that supply calories: protein and carbohydrate provide about 4 kcal per gram and fat about 9 kcal per gram. Once you know your calorie target, choosing a percentage split turns it into gram targets you can track on a food label or app.
The presets are common starting points rather than rules. Higher protein helps preserve muscle while dieting and keeps you fuller; more carbohydrate supports hard or long training; low-carb and keto splits trade carbohydrate for fat. All of them fall within or near the broad ranges health authorities consider acceptable for adults (10–35% protein, 45–65% carbs and 20–35% fat), except the deliberately low-carb options.
Hitting your calorie total consistently matters more for weight change than the exact split. Pick a split you can stick to, track for a couple of weeks, and adjust. This is general information, not medical or dietetic advice.
Frequently asked questions
Does alcohol count toward my macros?
Alcohol provides about 7 kcal per gram but is not one of the three macronutrients. If you drink, those calories come out of your total, usually by trimming carbs or fat.
Should I count fiber as carbohydrate?
Labels in the US include fiber in total carbohydrate. Fiber provides fewer usable calories, so some people track "net carbs", but for most goals counting total carbs is simpler and fine.