Guide, in Muscle Gain
How to Calculate Macros for Bulking: A Complete Guide
Bulking doesn't mean eating everything in sight. In a meta-analysis of 49 trials, extra protein stopped adding fat-free mass beyond a total of about 1.6 g per kg of body weight a day, with an upper confidence limit of 2.2 g/kg (Morton 2018). A controlled surplus with enough protein builds muscle with less fat than an unplanned one. How large a surplus maximises muscle gain has not been settled in trials, so most coaches start small and adjust from the scale.
7-minute read. Published Apr 2, 2026. Updated Oct 19, 2026. By AI Fit Hub.
Before you start
Set up the inputs that make the next steps easier
Guide steps
Move through it in order
Each step focuses on one decision so you can keep momentum without losing the thread.
- 1
Set your calorie surplus at TDEE + 200-300
Start with a modest surplus, around 250 calories a day, and adjust from your weekly average weight. Muscle is gained slowly, so a large surplus mostly adds fat. A review of off-season nutrition suggests gaining about 0.25-0.5% of body weight a week if you are a novice or intermediate, and less if you are advanced (Iraki 2019). If you gain faster, the excess is likely fat; if the scale has not moved in 3-4 weeks, add 100 calories.
Front-load your surplus on training days. Eat TDEE + 400 on training days and TDEE on rest days — the weekly average is still a surplus, but calories are better timed.
Use the TDEE Calculator: Estimate your daily energy expenditure with Mifflin-St Jeor + activity factors.
- 2
Set protein at 1.6-2.2g per kg bodyweight
This is the range with the strongest evidence: fat-free mass gains plateaued at about 1.6 g/kg, with an upper limit of 2.2 g/kg (Morton 2018). For an 80 kg lifter, 128-176 g of protein a day. Needs are higher in a deficit than in a surplus (Helms 2014), so 1.6-2.0 g/kg is a practical target during a bulk.
Spread protein across 4+ meals with at least 25-40g per meal to maximize muscle protein synthesis at each feeding.
Use the Protein Intake Calculator: Get daily protein targets based on training level and goal.
- 3
Set fat at 0.7-1.0g per kg bodyweight
Fat supports hormone production and the absorption of fat-soluble vitamins. For an 80 kg lifter, 0.7-1.0 g/kg is 56-80 g of fat a day. Very low-fat diets are best avoided, and physique-sport guidelines put fat at 15-30% of calories (Helms 2014); at 3,100 kcal, 75 g of fat is about 22%.
Focus on unsaturated fats (olive oil, nuts, avocado, fatty fish) while keeping saturated fat below 10% of total calories.
- 4
Fill the rest with carbs
After setting protein and fat, fill the remaining calories with carbohydrates. Carbs are the primary fuel for high-intensity resistance training — they replenish muscle glycogen, support training performance, and have a protein-sparing effect. For an 80 kg male at 3,100 kcal with 160g protein (640 kcal) and 75g fat (675 kcal): remaining = 1,785 kcal = ~446g carbs. That's a lot of carbs — and it's exactly what fuels hard training.
Time most carbs around training: 30-60g pre-workout, 60-100g post-workout, and the rest spread across other meals.
Use the Macro Calculator: Convert calorie targets into protein, carbs, and fat grams for your goal.
- 5
Track weight weekly and adjust after 3-4 weeks
Weigh yourself daily, calculate the weekly average. Target: about 0.25-0.5% of body weight a week for novices and intermediates (0.2-0.4 kg a week at 80 kg), or about 0.5-1% a month if you are advanced (Iraki 2019). If you're gaining faster, reduce surplus by 100 kcal. If you're not gaining, increase by 100 kcal. If you're gaining but it's mostly in your midsection with no visible muscle changes, you may need to improve your training stimulus rather than eat more.
Take progress photos every 2 weeks in the same lighting and angles. The mirror is a better judge of bulk quality than the scale alone.
Common mistakes
The misses that undo good inputs
Setting the surplus too high (500+ calories)
Muscle is gained slowly, so a large surplus provides energy that mostly ends up as fat. The result is a longer cut afterwards to reveal the muscle you built. A modest surplus with weekly weigh-ins keeps the gain closer to lean tissue.
Neglecting carbs to maximize protein
Protein above about 2.2 g/kg does not add muscle (Morton 2018), while too little carbohydrate can limit training quality. Once protein is covered, carbohydrate is usually the better use of the remaining calories for hard training.
Bulking without progressive overload in the gym
A calorie surplus without a progressively harder training stimulus just makes you fatter. The surplus provides raw materials; the training tells your body to use them for muscle. If you're not adding reps or weight to your lifts over time, extra calories have nowhere productive to go.
Questions people ask next
Can you build muscle without a surplus?
Yes, but much more slowly. Beginners and people returning from a break can build muscle at maintenance or even in a mild deficit (body recomposition). However, once you're past the beginner stage, a modest surplus accelerates muscle gain significantly — the research is clear on this.
How long should a bulk last?
Typically 3-6 months, ending when the rate of fat gain or your body fat level becomes uncomfortable for you, then followed by a cut or a maintenance phase. There is no evidence-based body-fat cut-off for ending a bulk; many lifters use their waist measurement and how their training is going.
What macro split should I use?
A good starting point for bulking: 25% protein, 50% carbs, 25% fat. Adjust based on preference — some people perform better with higher carbs (55-60%), others with slightly higher fat (30%). The protein target matters most; carb/fat ratio is secondary.
How do I know if I am gaining too much fat during a bulk?
If you are gaining faster than about 0.5% of body weight a week (or 1% a month if you are advanced), or your waist circumference is increasing faster than your chest and shoulders, you are likely gaining excess fat. Reduce your surplus by 100-150 kcal and reassess after 2 weeks.
Sources
- A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults , British Journal of Sports Medicine (2018) — Morton et al.
- A Systematic Review of Dietary Protein During Caloric Restriction in Resistance Trained Lean Athletes: A Case for Higher Intakes , International Journal of Sport Nutrition and Exercise Metabolism (2014) — Helms et al.
- Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation , Journal of the International Society of Sports Nutrition (2014) — Helms, Aragon & Fitschen
- Nutrition Recommendations for Bodybuilders in the Off-Season: A Narrative Review , Sports (2019) — Iraki, Fitschen, Espinar & Helms