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Macro Calculator

Calories decide weight; macros decide composition.

Two diets with identical calories can produce completely different physiques — the difference is macronutrient split. This calculator estimates your maintenance calories with the Mifflin-St Jeor equation, adjusts for your goal (cut, maintain, or bulk), then splits the total into evidence-based targets: protein anchored to body weight, fat set to support hormones, and carbs filling the rest.

Why people use this

People use this when calories alone stop working: two diets with identical calories build different bodies depending on the protein/carb/fat split. It is the starting point for meal prep, the number MyFitnessPal asks for, and the answer to "how much protein do I actually need?"

How it works

1. Enter weight, height, age, and sex for the Mifflin-St Jeor BMR estimate.
2. Pick your honest activity level — most people overestimate by one tier.
3. Choose a goal: fat loss (−20% calories), maintenance, or muscle gain (+10%).
4. Protein is set at 1.6–2.0 g/kg (higher when cutting), fat at 25% of calories, carbs take the remainder.

Common questions

Why does protein go up when cutting?

In a deficit, higher protein (around 2 g/kg) protects muscle mass — research consistently shows high-protein cuts preserve more lean tissue than low-protein ones at the same calories. Muscle is what keeps the weight off afterward.

How closely do I need to hit these numbers?

Calories and protein within ±10% covers ~90% of results. Carb and fat split can flex day to day — total weekly intake matters more than any single day's precision.

Should I eat back exercise calories?

No — the activity multiplier already includes them. Fitness trackers overestimate burn by 20–50%, so "eating back" their numbers is the most common reason diets stall.

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