Macro Calculator for Muscle Gain
A good bulk builds muscle, not just scale weight. Enter your details and get a lean-bulk macro split locked for muscle gain: a modest 250 kcal surplus, protein at 1.8 g per kg for growth, and carbs kept high enough to fuel progressive training.
Your results
Protein-first lean-bulk split from the Mifflin-St Jeor equation, a commonly used and validated estimation formula.
Your daily macro split
| Per meal (4 meals/day) | Target |
|---|---|
| Proteinthe anchor of every meal | |
| Carbohydratesmostly around training | |
| Fatspread through the day |
⚠ This target is very low. Dropping below roughly 1,200 kcal/day (women) or 1,500 kcal/day (men) without medical supervision risks muscle loss and slower healing. Pick maintenance or talk to us first.
How this muscle-gain macro calculator works
This page runs one locked calculation: your maintenance calories, plus a lean surplus, split protein-first. The math is shown in full below, so you can verify every number the tool gives you:
Protein is set first
At 1.8 g per kg, protein is fixed from your body weight before anything else, sitting just under the ceiling where extra protein stops building extra muscle.
Fat takes its share
About a quarter of your calories go to fat, enough for hormones and steady energy through long training days.
Carbs fill the gap
Everything left becomes carbohydrates: the fuel for progressive overload. On a lean bulk this is usually a generous amount, which is exactly the point.
Check the math: a worked example
Take a 30-year-old man, 75 kg, 172 cm, lightly active. Here is every step, with nothing hidden:
Run the same inputs through the calculator above and you will get the same numbers. That is the point: a tool you can audit is a tool you can trust.
Lean bulk, not dreamer bulk
The difference between a lean bulk and a dirty bulk is not discipline, it is math. Muscle grows slowly: even in a perfect month, a trained lifter might add half a kilo of actual muscle tissue. Everything above that on the scale is mostly fat and water.
A 250 kcal surplus respects that speed limit. It gives the body slightly more energy than it needs, so muscle has material to grow, without flooding it with far more than it can use. Push the surplus to 750 or 1,000 kcal and muscle does not grow three times faster. Fat does.
Here is the physiotherapist’s objection to dreamer bulking: fat is load. The same research that shows each pound lost unloads about four pounds of pressure from the knee works in reverse for every pound gained. Lifters who bulk aggressively often arrive stronger but with achier knees, crankier lower backs and worse sleep. The goal was muscle. The scale was only ever a proxy for it.
Protein at 1.8 g per kg, and why more is not better
More protein is not always better; there is a ceiling, and this calculator sits just under it. The research consensus puts the muscle-building range at roughly 1.6 to 2.2 g per kg per day. Past that point, extra protein does not build extra muscle. It just becomes expensive energy, doing the same job cheaper carbs could do.
At 1.8 g/kg, a 75 kg lifter lands at 135 grams a day: enough to maximize growth, with headroom for hard training blocks. Older lifters and anyone returning from a layoff should stay near the top of the range, since both situations make the body less efficient at using protein.
The per-meal table matters here too. Four meals at around 34 grams each keeps muscle-building signals firing through the day, which beats back-loading most of your protein into one evening feast.
Carbs are your training fuel
On a bulk, carbohydrates are not the enemy of leanness; they are the fuel of progression. Progressive overload, adding weight or reps over time, is what forces muscle to grow, and hard sets run on glycogen. Lifters who bulk on very low carbs usually stall first in the gym, which defeats the purpose.
That is why this calculator sets protein and fat first, then gives carbohydrates everything left over. On a 2,560 kcal lean bulk that works out near 345 grams: plenty of fuel for four or five hard sessions a week, with room for rice, oats, potatoes, fruit and whole-wheat roti.
Time the bulk of your carbs around training if you like, a solid meal two to three hours before and another after, but do not overthink it. Total daily intake drives results; timing is a small optimization on top.
How fast to gain, and when to stop
Expect the scale to move about 0.25 kg per week on a true lean bulk. Faster than that for several weeks running, and you are mostly adding fat; the surplus is bigger than your training can use, so trim 100 to 150 kcal from carbohydrates.
Run the bulk for three to six months, then reassess honestly. Useful stop signs: your waist is growing faster than your lifts, sleep quality has dropped, or joints that were quiet have started complaining. None of those mean bulking failed; they mean this phase has done its job and it is time to hold at maintenance for a while or run a short cut.
One more checkpoint from the clinic: if you are gaining weight but your training numbers are frozen, food is not the problem. The program is. Fix progression before adding more calories.
Do not bulk through pain
A surplus is not a license to train injured. Extra body weight plus heavy loading is exactly how cranky knees and backs get worse, and eating more does not speed up a tendon that needs relative rest.
If something hurts beyond normal muscle fatigue for more than two weeks, get it assessed instead of eating through it. The muscle you built will still be there after a smart rehab block; the injury you ignored can cost you a year. This calculator carries a rehab note in the results for exactly this reason.
Macro calculators for every goal
This page is tuned for muscle gain. The same validated formula powers calculators for the other goals:
Macro Calculator
The full version: fat loss, maintenance and muscle gain in one tool, with the complete macro guide.
Macro Calculator for Weight Loss
Higher protein and a steady 500 kcal deficit, built to cut fat while keeping the muscle that protects your joints.
Keto Macro Calculator
Carbs capped for ketosis, protein kept moderate, with the electrolyte cautions most keto guides skip.
Macro Calculator for Women
Protein targets that account for muscle preservation, bone health and training through hormonal cycles.
Want your maintenance calories first? Start with our TDEE calculator, then come back here to split them into macros.
Muscle-gain macros: frequently asked questions
How big should my calorie surplus be?
About 250 kcal above maintenance per day, which is what this calculator sets. That supports roughly 0.25 kg of scale gain per week. Larger surpluses do not build muscle faster; past 300 to 400 kcal the extra intake mostly becomes fat.
Will I gain fat as well as muscle?
Yes, some. Even a well-run lean bulk adds a mix of muscle and fat; roughly half and half is common. If the scale is climbing much faster than 0.25 kg a week or your waist is outpacing your lifts, the surplus is too big. Trim 100 to 150 kcal from carbohydrates and reassess in two weeks.
Does protein timing matter?
Total daily protein matters far more than timing. Spreading it across three to five meals keeps muscle-building signals firing through the day, which is why this calculator shows per-meal targets. The old 30-minute post-workout window is overstated; just eat a solid meal within a few hours of training.
How long should I bulk for?
Three to six months suits most lifters. Then reassess: if body fat has climbed more than you are comfortable carrying, or joints that were quiet have started aching, hold at maintenance for a month or run a short cut. Endless bulking just raises the body-fat set point you will have to diet off later.
What if I am gaining weight too fast?
First confirm it is a trend, not a fluctuation: compare weekly averages, not single weigh-ins. If the average is climbing well above 0.25 kg per week, cut 100 to 150 kcal from daily carbohydrates and hold training steady. Do not slash the surplus to zero; a tiny surplus still builds muscle.
Can I build muscle and lose fat at the same time?
Beginners, detrained lifters returning after a layoff, and people with higher body fat often can, at maintenance calories with high protein. Experienced, already-lean lifters do better picking one goal at a time. If that is you, run this lean-bulk calculator for a dedicated gaining phase, then cut with the weight-loss version.
PhysioUBK Health Tools · Estimates only, not medical advice · physioubk.com