Calculate your lean-bulk macros
Enter your details. The calculator estimates BMR with the Mifflin-St Jeor equation, multiplies by activity to get TDEE, adds your chosen surplus, then splits the target: protein from body weight (1.6–2.2 g/kg), fat at 20–30% of calories, and carbs getting the remainder.
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How it works
1. BMR is estimated with the Mifflin-St Jeor equation from age, sex, weight and height. 2. An activity multiplier (1.2–1.9) gives TDEE. 3. Your surplus is added (+5/+10/+15%). 4. The target is split: protein 1.6–2.2 g/kg of body weight, fat 20–30% of target calories, carbs = the remainder — carbs stay high because training fuel matters most when building.
Worked example — 30-year-old woman, 70 kg, 165 cm, moderately active, +10% surplus, protein 1.8 g/kg, fat 25%
- BMR: 10×70 + 6.25×165 − 5×30 − 161 = 1,420 kcal
- TDEE: 1,420 × 1.55 = 2,201 kcal
- Daily target: 2,201 × 1.10 = 2,422 kcal/day
- Protein: 1.8 × 70 = 126 g (504 kcal)
- Fat: 25% of 2,422 = 606 kcal ÷ 9 = 67 g
- Carbs: (2,422 − 504 − 606) ÷ 4 = 328 g
- Expected gain: 0.25–0.5% of 70 kg = 0.18–0.35 kg/week
Check the arithmetic: 504 + 606 + 1,312 = 2,422 kcal. Try these exact inputs in the calculator above — you should get the same numbers.
Lean bulk vs dirty bulk
A "dirty bulk" eats a large surplus (often 500–1,000+ kcal over TDEE) with little attention to macros. It gains weight fast — but muscle growth has a speed limit, and calories beyond that limit mostly become fat, which you then have to diet off, losing some of the muscle you built. A lean bulk uses a small, measured surplus (5–15%) so most of the gain is lean tissue and the eventual cut is short.
Surplus sizes at a glance
| Surplus | Size | Best for |
|---|---|---|
| Lean | +5% of TDEE | Slow, minimal-fat gains; people who gain fat easily |
| Moderate | +10% of TDEE | The default — solid growth with controlled fat gain |
| Aggressive | +15% of TDEE | Hard gainers or people with a long training history stalling |
Expected gain rate by body weight
| Body weight | 0.25%/week | 0.5%/week |
|---|---|---|
| 60 kg | 0.15 kg/week | 0.30 kg/week |
| 70 kg | 0.18 kg/week | 0.35 kg/week |
| 80 kg | 0.20 kg/week | 0.40 kg/week |
| 90 kg | 0.23 kg/week | 0.45 kg/week |
Use the scale to steer the surplus: if weight climbs well above 0.5% per week for several weeks, step the surplus down (e.g. +15% → +10%); if it barely moves after 2–3 weeks, step it up. Strength training is the non-negotiable part — a surplus without progressive training just adds fat.
Protein timing: daily total beats the "anabolic window"
The old rule was to rush protein within 30–60 minutes after training. Current evidence shows the daily total matters far more than the clock. Practical targets: eat 3–5 protein feedings of 20–40 g each across the day, with one feeding in the few hours around your workout. That covers almost all of timing's benefit with none of the stress.
Note: More protein is not always better. Around 1.6–2.2 g/kg/day is the evidence-based range for muscle growth; pushing past ~2.2 g/kg has no clear added benefit and steals calories from carbs, which fuel the training that actually builds the muscle.
Interpreting your results
Daily calorie target is the number to eat consistently — the surplus is already added. Protein grams are the priority: spread them over the day. Carb grams look high on purpose; carbs are training fuel, and a bulking diet is where they do the most work. Fat grams stay moderate for hormones and food enjoyment.
Your timeline uses the middle of the 0.25–0.5%/week range (~0.375%/week of current weight). Judge progress by the weekly average weight, not one morning, and give each adjustment 2–3 weeks before changing anything — the scale is noisy in the short term.
Related calculators
Macro Calculator — daily calories, protein, carbs and fat from your body, activity and goal.
Protein Calculator — how much protein you need per day, from body weight and activity.
TDEE Calculator — your total daily energy expenditure from BMR and activity level.
BMR Calculator — your basal metabolic rate, the calories burned at complete rest.
Lean Body Mass Calculator — your lean body mass in kg plus an estimated body fat percentage.
Body Fat Calculator — estimate your body fat percentage from simple body measurements.
Pace Calculator — running pace, race time and distance from any two of the three, in km or miles.
Calorie Deficit Calculator — find your daily calorie target for weight loss, with macro grams and a goal timeline.
Diet Macro Presets — keto, low-carb, high-protein and balanced macro ratios turned into daily grams.
Best Macro Ratio for Weight Loss — guide to protein, ratios and adjusting your split in a deficit.
What Is IIFYM — explainer guide to "If It Fits Your Macros".
Macros 101 — beginner guide to protein, carbs and fat and how to start tracking.
How to Calculate Your Macros — step-by-step guide: BMR, TDEE, goal calories, protein, fat and carbs, with a worked example.
Weight Loss Macro Calculator — protein-first macro targets, deficit safety floor and goal timeline for fat loss.
Keto Macro Calculator — keto fat, protein and net-carb grams from your calories and preset ratio.
Frequently Asked Questions
How much protein do I need to build muscle? About 1.6 to 2.2 g per kg of body weight per day. This calculator defaults to 1.8 g/kg — for a 70 kg person, that is 126 g of protein daily.
What is a good calorie surplus for muscle gain? A lean-bulk surplus of about 5 to 15% above TDEE. +10% is a good default: enough to grow, small enough that most of the gain is lean tissue.
How fast should I gain weight on a lean bulk? About 0.25 to 0.5% of body weight per week — for a 70 kg person, roughly 0.18 to 0.35 kg per week. Much faster usually means adding more fat than muscle.
Does protein timing matter for muscle gain? Daily total matters most. Spread protein over 3–5 meals of at least 20–40 g each and you cover the small extra benefit of pre/post-workout timing. No magic window exists.
Should I eat more on training days? Weekly average calories matter more than daily precision. A steady daily target is simpler and works fine; day-to-day cycling is optional, not required.
What if I gain weight faster than the target rate? If the scale climbs well above ~0.5% of body weight per week for several weeks, trim the surplus a step (for example +15% to +10%). If it barely moves after 2–3 weeks, raise the surplus a step.
Is this medical advice? No. This is general information only. Talk to a doctor or registered dietitian before changing your diet, especially if you are pregnant, have diabetes, kidney disease, or any health condition.