Macro Calculator
Free macro calculator that splits daily calories into protein, fat, and carb grams. Supports cut, maintain, bulk, keto, low-carb, and high-protein presets.
A macro calculator splits your daily calorie target into the three macronutrients — protein, fat, and carbohydrate — so you have a concrete number to aim at for each. Without this split, "eat 2,500 calories" is too vague to act on. With it, you know to hit ~165 g protein, 75 g fat, and the rest in carbs.
This tool sets protein first (2.2 g per kg of body weight), fat second (75 g as a hormone floor by default, or shifted higher for keto and low-carb), and carbs fill the remaining calorie balance. That order isn’t arbitrary — protein is the most metabolically expensive and the macro with the most muscle-building leverage, so locking it in first is the evidence-based move. The same logic powers MuscleBuddy’s nutrition engine, which then adjusts the numbers weekly based on your actual weigh-in trend.
How this works
The calculator runs in two stages. First it computes your maintenance calories (TDEE) from the Mifflin-St Jeor BMR formula multiplied by an activity factor, then it adjusts that baseline by ±500 kcal depending on whether you’re cutting, maintaining, or bulking. That gives you a target calorie level — but calories alone aren’t enough.
Stage two converts the calorie target into macro grams in a fixed order:
- Protein: 2.2 g per kg of body weight (≈1 g per pound). This is the upper end of the research-backed range for muscle protein synthesis in trained athletes.
- Fat: 75 g baseline (covers hormone production for most adults). Keto shifts to 70% of calories from fat; low-carb to 40%.
- Carbs: fills the remaining calorie balance — typically 200–400 g for most lifters on a standard split.
Why protein stays high in both cut and bulk: during a calorie deficit, high protein preserves lean mass that would otherwise be burned for fuel; during a surplus, it maximizes muscle protein synthesis. There’s essentially no downside to keeping protein elevated.
Why fat has a floor rather than a percentage: testosterone, estrogen, and other steroid hormones depend on dietary fat. Drop too low and hormone production suffers. 0.6–1.0 g/kg is the safe range for almost all adults; 75 g covers most body weights without forcing the math.
Why carbs flex: they’re the macro most directly tied to training performance, but they’re also the easiest to manipulate up and down depending on the day’s calorie target. Carb cycling — high days on training, low on rest — is a more advanced version of this idea.
Frequently asked questions
- How much protein do I need to build muscle?
- Research consistently lands around 1.6–2.2 grams per kilogram of body weight (roughly 0.7–1.0 g per pound). MuscleBuddy uses 2.2 g/kg as a reliable target for trained lifters in any phase.
- Why does fat stay constant at 75 grams in the standard split?
- Fat needs to stay high enough to support hormone production — broadly above 0.6 g per kg of body weight. 75 g covers most adults and keeps the protein and fat targets steady so carbs flex with calorie goal.
- Do I need to track carbs strictly?
- Carbs fill the calorie balance after protein and fat are set. Hitting your calorie and protein targets matters more than precise carb numbers — but consistent carb intake helps training performance and recovery.
- What is a keto macro split?
- Keto runs ~70% of calories from fat, moderate protein, and under 50 g of carbs per day. The calculator includes a keto preset that auto-shifts fat upward and carbs near zero.
- Should I eat the same macros every day?
- Constant macros work well for cuts and bulks where consistency is the priority. For more advanced goals, carb cycling (high/low days) or refeeds can preserve metabolic rate during prolonged dieting.
- How often should I update my macro targets?
- Every 4–6 weeks, or whenever your weigh-in trend stalls or runs off the rails. Macros that worked a month ago drift out of date as body weight changes.
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