Macro Calculator 🔒 Runs locally in your browser — nothing is uploaded.

Protein, carb & fat split calculator

For informational purposes only — not medical advice. Consult a healthcare professional or registered dietitian before making significant changes to your diet.

Enter a calorie target you already know. This tool splits it into macros — it doesn't calculate your calorie needs for you.

Ratios are protein / carbs / fat, as % of total calories.

Current total: 100%

Optional — cross-checks your protein total against the commonly cited athletic guideline of 1.6–2.2 g per kg of bodyweight. Informational only, not a hard rule.

Protein — — Carbs — — Fat — —
Macro % of calories Calories Grams
Protein — — —
Carbs — — —
Fat — — —
Total — — —
Below the typical range Within the typical range Above the typical range
—
Commonly cited athletic guideline: 1.6–2.2 g protein per kg bodyweight.

About this tool

Every gram of food you eat contributes calories through three macronutrients — protein and carbohydrates each supply 4 kcal per gram, while fat supplies a denser 9 kcal per gram. A "macro split" just describes what percentage of your daily calories comes from each: a balanced plan built around 30% protein / 40% carbs / 30% fat, a low-carb plan that shifts more of those calories to protein and fat, or a very low-carb keto plan that puts most calories into fat. This calculator takes the daily calorie target you already have in mind, applies your chosen split, and converts each percentage into grams so you know how much protein, carbs and fat to actually aim for at the table.

These presets are widely cited starting points, not personalized prescriptions — the right split for you depends on your goals, activity level, medical history and how your body responds, which is exactly the kind of judgment call a doctor or registered dietitian is trained to help with. The optional bodyweight field adds one more commonly cited reference point: many strength and endurance athletes target roughly 1.6 to 2.2 grams of protein per kilogram of bodyweight, and this tool shows where your calculated protein total falls against that range — purely as a sanity check, never as a target you must hit. Everything runs locally in your browser; no numbers you enter are ever sent anywhere.

Frequently asked questions

Which diet preset should I choose?

There's no universally "best" split — it depends on your goals, preferences, and how your body responds. Balanced is a reasonable general-purpose starting point for most people; High-protein is often favored during fat-loss phases to help preserve muscle; Low-carb/Keto suits people who specifically find those eating patterns easier to stick to or who have discussed them with a healthcare provider for a specific reason. Whichever you pick, the best diet is ultimately the one you can consistently sustain — consider trying Custom to fine-tune ratios based on how you actually feel and perform over a few weeks.

Why does fat use 9 calories per gram while protein and carbs use 4?

This comes from the Atwater system, a well-established, long-standing set of average energy values based on the actual chemical structure of each macronutrient — fat molecules contain more energy-dense carbon-hydrogen bonds per gram than protein or carbohydrate molecules do, which is measurable directly via bomb calorimetry (burning a sample and measuring the heat released). These are the same standard conversion factors used on nutrition labels worldwide, not something specific to this calculator.