The internet is full of macro calculators that spit out three numbers, tell you to eat them, and disappear. Most of them are set up to fail because they skip the two variables that decide whether the plan actually adds muscle: how much you eat above maintenance, and where that surplus is coming from. This guide gives you the numbers, the reasoning behind them, and the check-in loop that keeps your macros working past week four.

The Short Version

For most lifters trying to add lean mass, the target split looks like this:

  • Calories: maintenance (TDEE) + 200–300 kcal for a lean bulk; +500 kcal for a faster bulk with more fat gain.
  • Protein: 1.6–2.2 g per kg of bodyweight per day.
  • Fat: 0.8–1.2 g per kg of bodyweight per day (minimum 20% of total calories).
  • Carbs: whatever is left in your calorie budget.

Everything else on this page is context, adjustment logic, and why these ranges work.

Step 1 — Find Your Real TDEE

You cannot design a bulk without knowing what maintenance actually is. Run your numbers through our TDEE calculator (Mifflin-St Jeor equation with an honest activity multiplier). Two rules that keep this step from wrecking the plan:

  • Be honest about activity. Most people overestimate. If you sit at a desk and train 3–4 times a week, you are "light" (1.375), not "moderate" (1.55).
  • Verify before you trust. Eat at the predicted maintenance for two weeks, weigh yourself every morning fasted, average by week. If bodyweight is flat, your TDEE guess is correct. If it drifts up or down more than 0.3 kg per week, adjust by ±150 kcal and re-check.

Two weeks of calibration beats any calculator on the internet.

Step 2 — Set the Surplus

The surplus size is a direct trade-off between speed of gain and fat-to-muscle ratio. The research on natural lifters (Aragon & Schoenfeld 2013, Helms et al. 2014, Iraki et al. 2019) converges on three brackets:

  • Lean bulk (+200–300 kcal / day): ~0.25–0.5% bodyweight gained per week. Roughly 70% of the gain is lean mass. Best for anyone past the newbie window.
  • Standard bulk (+400–500 kcal / day): ~0.5–1% bodyweight per week. Roughly 60% lean. Fine for true novices in the first 12 months of training.
  • Aggressive bulk (+700+ kcal / day): 1–2% per week. Lean-mass ratio drops to 40–50%. Almost never worth it unless you are underweight for your frame.

If you are past year one of consistent training, default to the lean-bulk bracket. The extra calories in a bigger surplus buy fat, not muscle, past a certain point — a phenomenon sometimes called the "muscle-full effect".

Step 3 — Lock In Protein

Protein is the non-negotiable macro. Every meta-analysis on the topic (Morton et al. 2018, Schoenfeld & Aragon 2018) lands on the same range: 1.6 to 2.2 g of protein per kg of bodyweight per day maximizes muscle-protein synthesis in trained lifters.

  • Lower end (1.6 g/kg): fine if you are on a modest surplus with adequate calories and good sleep.
  • Higher end (2.2 g/kg): useful if you are older (35+), sleep is compromised, or training volume is high.
  • Above 2.5 g/kg: not harmful for healthy kidneys, but no additional benefit. Just displaces carbs or fats and costs money.

Distribute across 3–5 meals of roughly equal protein content. A single 60 g protein bolus at dinner does not do the same job as 25 g protein across four evenly spaced meals.

Step 4 — Set Fat, Then Fill With Carbs

Fat has two jobs during a bulk: keep hormones running (especially testosterone in men) and make food palatable enough that you can actually hit the calorie target day after day.

  • Minimum: 0.7 g/kg bodyweight, or 20% of total calories, whichever is higher.
  • Typical range: 0.8–1.2 g/kg. Comfortable and hormonally safe.
  • Above 1.5 g/kg: starts cutting into carb budget without benefit.

Once protein and fat are set, carbs get the remaining calories. Carbs are the workout fuel — they refill muscle glycogen, drive training performance, and are the cheapest per-calorie macro to hit.

Worked Example — 80 kg Male, Lean Bulk

Here is what the numbers look like for a typical lifter putting the pieces together:

  • TDEE (moderately active): 2,800 kcal
  • Bulk target: TDEE + 250 = 3,050 kcal
  • Protein: 80 × 2.0 = 160 g → 640 kcal (21% of total)
  • Fat: 80 × 1.0 = 80 g → 720 kcal (24%)
  • Carbs: 3,050 − 640 − 720 = 1,690 kcal → 423 g (55%)

You can plug those same numbers into our Macro Matrix calculator and pick the "Muscle Gain" goal to see a similar split automatically.

Split Profiles — Balanced vs High-Protein vs Low-Carb

Not every lifter thrives on the "standard" split. Two common variations:

  • High-protein (40/35/25 P/C/F): useful if you are older, under-recovered, or nutrient-dense budget conscious. Protein is filling and thermogenic — appetite management is easier.
  • Low-carb (35/25/40 P/C/F): only if you have a specific reason (blood sugar management, personal preference, low-training-volume phase). Bulking on low carbs is possible but training performance often drops.

The "balanced" 30/40/30 split is the default because it is the profile that most lifters can adhere to for months without breakdown, which is the actual limiting factor for progress.

The Adjustment Loop

This is where most people fail. Bodyweight adaptation slows every 4–6 weeks, and the initial macro numbers stop working. Bake this loop into your routine:

  • Weigh yourself every morning, fasted, post-bathroom. Same scale, same conditions.
  • Each Sunday, average the past 7 days. That is your weekly bodyweight.
  • Every 2 weeks, compare your weekly average to two weeks prior:
    • Gained 0.25–0.5% of bodyweight: on target, hold macros.
    • Gained less than 0.25%: add 150 kcal (usually as carbs).
    • Gained more than 0.6%: cut 100 kcal or add a light walk 3× per week.
    • Flat or losing: something else is wrong (poor tracking, high stress, sleep, illness). Investigate before adding calories.

Common Mistakes That Kill Muscle-Gain Progress

  • Under-eating on training days. A "bulk" that averages TDEE + 250 kcal but sits at TDEE − 100 kcal on rest days is really just a maintenance cut. Track daily totals, not week-average estimates.
  • Chasing arbitrary macros over calories. Hitting protein exactly but under-eating carbs by 100 g means you missed 400 kcal — that is the whole surplus gone.
  • Recalculating TDEE only at the start. Your TDEE goes up as you gain lean mass. A 5 kg heavier version of you burns ~100 kcal more at rest. Recalculate every 6–8 weeks.
  • Comparing to Instagram progress. Enhanced athletes gain lean mass at 3–5× the natural rate. If your bulk is producing 0.3 kg per week of mixed gain, you are on pace.

When the Bulk Should End

Two useful stopping criteria:

  • Body fat above 18% (men) or 25% (women). Above these thresholds, insulin sensitivity drops and further gains skew toward fat. Cut back to 12% / 20% before bulking again.
  • Diminishing returns. If two consecutive 2-week check-ins show less than 0.15% weekly gain despite a +250 kcal surplus, you may be near your natural muscle-mass ceiling for the current training age. Consider a short maintenance phase or an intensified program before pushing calories higher.

Bottom Line

A macro calculator for muscle gain is not magic. The formula is: real TDEE + a 200–500 kcal surplus, 1.6–2.2 g/kg protein, 0.8–1.2 g/kg fat, carbs fill the rest, and a 2-week check-in loop that adjusts as your body responds. Everything else — meal timing, precise macro ratios, supplement stacks — is a rounding error on top of these four decisions. Run your numbers, hold protein, keep the surplus modest, and let 8–12 weeks of consistent tracking do what a perfect starting split cannot.