🍗 Macro Split Calculator for Cutting & Bulking

Last updated: March 25, 2026

Macro Split Calculator

Get exact protein, carb & fat targets for your calorie goal

Your Daily Macros
Protein
—
grams
Carbs
—
grams
Fat
—
grams
—% Protein —% Carbs —% Fat

Why Your Macro Ratio Matters More Than Your Calorie Number Alone

Most people count calories. Fewer people count macros. And almost nobody does both correctly for their specific goal at their specific bodyweight — which is exactly why so many cut phases end in muscle loss, and so many bulk phases end in a surprising amount of fat gain.

The three macronutrients — protein, carbohydrates, and fat — each carry different caloric densities and serve entirely different physiological roles. Protein and carbohydrates each deliver 4 calories per gram. Fat delivers 9. But that arithmetic is the easy part. The harder question is: given your goal, your bodyweight, and a fixed daily calorie ceiling, how should you distribute those calories across three buckets so that your body does exactly what you want?

The Physiology Behind a Cut: Keeping Muscle While Burning Fat

When you eat less than you burn — a caloric deficit — your body must find fuel somewhere. The ideal outcome is that it raids your fat stores. The nightmare outcome is that it cannibalizes lean muscle. Which one actually happens depends heavily on how much protein you're eating.

Research consistently shows that protein intakes of around 2.2–2.4 grams per kilogram of bodyweight during a deficit provide a powerful anti-catabolic signal. At that intake, muscle protein synthesis remains elevated enough to defend your lean tissue even while stored fat is being oxidized. Drop protein below 1.6g/kg during a cut and you're essentially accepting muscle loss as part of the deal — which tanks your metabolic rate and makes every subsequent cut harder.

Fat has a floor too. Dietary fat is essential for testosterone production, cellular membrane integrity, and fat-soluble vitamin absorption (A, D, E, K). Going below roughly 0.6–0.7g of fat per kilogram of bodyweight for extended periods suppresses hormone output noticeably. During a cut, keeping fat at about 25% of total calories typically threads this needle — enough to protect hormones without eating up too much of the calorie budget that protein needs.

Whatever calories remain after protein and fat are covered go to carbohydrates. On a cut, this "remainder" approach means carbs take the hit — and that's fine, because carbs are the one macronutrient with no strict minimum floor (beyond what's needed to fuel training).

The Physiology Behind a Bulk: Fueling Muscle Without Drowning in Fat

Bulking is the mirror image problem. You're eating above maintenance, so the risk isn't muscle loss — it's disproportionate fat accumulation. The goal is to create just enough of an anabolic environment that muscle protein synthesis is running at maximum, while keeping the calorie surplus tight enough that you're not also building a second layer of insulation.

During a surplus, protein targets can actually come down slightly compared to a cut — not because protein matters less, but because caloric abundance reduces muscle breakdown, so you don't need as high a dose to stay net-positive in muscle protein balance. Around 1.8–2.0g/kg is well-supported for bulking phases.

What changes dramatically is carbohydrates. Carbs replenish muscle glycogen, which is the primary fuel for high-intensity resistance training. Training on depleted glycogen is like trying to drive a race car on fumes — the engine is technically running, but it's not running well. A bulk macro split deliberately raises carb percentage because more training fuel means better sessions, more progressive overload, and ultimately more stimulus for muscle growth.

Fat stays moderate — elevated enough for hormonal health (around 28% of calories is a sensible target), but it doesn't need to climb much higher since fat doesn't directly contribute to muscle synthesis the way protein and workout-fueling carbs do.

Bodyweight Is the Missing Variable Most Calculators Ignore

Here's the flaw in generic macro split percentages like "40/40/20 for bulking" or "40/30/30 for cutting": they treat a 60kg woman and a 110kg man identically, as long as they're eating the same number of calories. That's wrong.

Protein needs are anchored to lean body mass, not to total calorie intake. A 60kg person cutting on 1,400 calories needs about 144g of protein (2.4 × 60). A 110kg person cutting on 2,400 calories needs about 264g (2.4 × 110). As a percentage of total calories, those two people look completely different — but both are meeting the biological requirement for their size. A percentage-only approach either overprovides protein for lighter people or underprovides it for heavier ones.

The correct method is to anchor protein to bodyweight first, set fat as a minimum floor percentage of total calories, and fill the remaining caloric room with carbohydrates. That's exactly the order of operations this calculator uses.

How to Actually Hit Your Numbers Every Day

Knowing your macro targets is step one. Consistently hitting them is a different skill. A few strategies that genuinely help:

Protein first, always. Plan your protein sources before anything else in a meal. Once you know you've got 40g of chicken, 30g of Greek yogurt protein, and a scoop of powder accounted for, the rest of the plate fills itself much more easily.

Fat tends to be passive. Cooking oils, egg yolks, nuts, and fatty fish add up quickly without much effort. Most people overshoot fat, not undershoot it. Track it, but don't agonize over hitting a fat target — focus your energy on protein and carbs.

Carb timing matters on bulk phases. Concentrating a larger portion of your carb intake around training — a meaningful pre-workout meal and a solid post-workout carb source — maximizes glycogen availability and recovery. On rest days, total carbs can be modestly lower without meaningful consequences.

Weekly averages beat daily perfection. If you hit 10g short on protein Monday but 15g over Tuesday, you're ahead for the week. Chasing exact daily numbers is useful when you're just starting out and learning what foods contain what amounts. But once you have a mental library of your regular meals, approximate consistency over the week is a more sustainable target than obsessing over each individual day.

One Last Thing: Adjust Based on What the Mirror and Scale Tell You

No calculator — including this one — knows your exact metabolic rate, your training volume, your sleep quality, or your stress hormones. The numbers you get here are an evidence-based starting point. Give them four to six weeks of honest adherence, then assess. If you're cutting and not losing weight despite hitting your calorie and macro targets, your actual maintenance is lower than estimated and you'll need to pull calories down slightly. If you're bulking and gaining fat faster than expected, tighten the surplus. The formula is the map, not the territory — and your body is always the most honest feedback mechanism you have.

FAQ

Why does the calculator use grams per kilogram for protein instead of a fixed percentage?
Because protein needs are tied to how much muscle mass you're trying to build or protect, and that scales with bodyweight — not with how many calories you're eating. A percentage-based approach gives too much protein to small people eating a lot of calories and too little to large people on a deficit. Anchoring protein to bodyweight first (2.4g/kg for cutting, ~2.0g/kg for bulking) ensures the biological requirement is met regardless of total calorie intake.
Is 2.4g of protein per kg of bodyweight really necessary when cutting, or is that overkill?
It's not overkill — multiple controlled trials (including Eric Helms' and Stu Phillips' research groups) show that higher protein intakes during energy restriction provide stronger protection against lean mass loss compared to intakes around 1.6g/kg. The surplus protein also has a slight thermic advantage: roughly 25–30% of protein calories are burned during digestion, which means a high-protein diet effectively costs fewer net calories than the label suggests.
Why does fat stay at a minimum percentage rather than being set to zero on a cut?
Dietary fat is essential for producing steroid hormones including testosterone, which directly supports muscle retention. It also enables absorption of fat-soluble vitamins A, D, E, and K. Dropping fat too low — typically below about 0.5–0.6g per kg of bodyweight — measurably suppresses testosterone in both men and women. Keeping fat at roughly 25% of calories during a cut maintains hormonal health without consuming a disproportionate share of the calorie budget.
Why do carbs get whatever calories are left over rather than being calculated directly?
Unlike protein and fat, carbohydrates have no strict physiological minimum that needs to be protected (your body can synthesize glucose via gluconeogenesis). This makes carbs the most flexible lever. By covering non-negotiable protein and fat targets first, then filling remaining calories with carbs, the calculator ensures biological minimums are always met while making the split adaptive to your specific calorie total and bodyweight combination.
How often should I recalculate my macros during a long cut or bulk?
Recalculate every 3–5 kg of bodyweight change, or every 8–10 weeks — whichever comes first. As your weight drops during a cut, your protein target (in absolute grams) decreases slightly. As you gain mass during a bulk, it increases. Running the same macro numbers you calculated at 90kg when you now weigh 82kg means you may be under-protecting muscle during the final phase of your cut, when the risk is actually highest.
Can I use this calculator if I follow intermittent fasting or eat only two meals a day?
Yes — the calculator gives you daily gram targets, not a meal-by-meal schedule. Whether you hit 180g of protein across six small meals or two large ones is a matter of personal preference and practicality. Research on meal frequency and muscle protein synthesis suggests that spreading protein across at least 3–4 eating occasions optimizes 24-hour muscle protein synthesis, but if your eating window only allows two meals, you can still hit your daily targets effectively with larger portions per sitting.