Bulking Macro Calculator
Enter your body weight and the daily surplus you want to run, and this bulking macro calculator returns your target calories plus daily grams of protein, carbohydrate, and fat for a lean bulk. You can type your maintenance calories (TDEE) or let the tool estimate them.
Your bulking macros
Eat about:
Daily macro targets
| Macro | Grams/day | Calories | % of total |
|---|---|---|---|
| Protein | 0 g | 0 kcal | 0% |
| Fat | 0 g | 0 kcal | 0% |
| Carbs | 0 g | 0 kcal | 0% |
Protein is set from your chosen grams-per-pound, fat at ~25% of total calories, and carbohydrates fill the rest to fuel training.
How to set your bulking macros
"Macros" are the three energy-providing macronutrients: protein, carbohydrate, and fat. Total calories decide whether you gain weight; the macro split decides how much of that weight is muscle versus fat. A good lean-bulk approach sets protein first, fat second, and lets carbohydrates fill whatever calories remain.
The math this calculator uses
Energy values are fixed: protein and carbohydrate each provide 4 calories per gram, and fat provides 9 calories per gram. The tool works in this order:
- Target calories = your maintenance (TDEE) + your chosen surplus.
- Protein = body weight (lb) × your grams-per-pound setting. The Academy of Nutrition and Dietetics and the International Society of Sports Nutrition support roughly 0.7-1 g per pound while building muscle.
- Fat = 25% of target calories ÷ 9.
- Carbs = remaining calories (target − protein calories − fat calories) ÷ 4.
Worked example. A 155 lb lifter with a 2,500 kcal maintenance picks a +500 surplus, so target = 3,000 kcal. Protein at 1 g/lb = 155 g (620 kcal). Fat at 25% = 750 kcal ÷ 9 = about 83 g. Carbs = (3,000 − 620 − 750) ÷ 4 = about 408 g. Those macros sum back to ~3,000 kcal, confirming the split.
Lean bulk vs dirty bulk
A moderate surplus of 250-500 kcal keeps fat gain modest while still feeding muscle growth — this is a lean bulk. Pushing the surplus much higher (a "dirty bulk") gains weight faster but a bigger share becomes fat, since the body builds muscle at a capped rate. If you struggle to hit your carb and calorie numbers, lean on calorie-dense foods and a homemade weight-gain shake.
Sources: Jäger R, et al. "International Society of Sports Nutrition Position Stand: Protein and exercise." J Int Soc Sports Nutr. 2017 (PubMed) · Academy of Nutrition and Dietetics · Examine.com — Protein intake · NIH / NIDDK.
Frequently asked questions
- What are good macros for bulking?
- A common lean-bulk split is about 1 gram of protein per pound of body weight, 25% of calories from fat, and the rest from carbohydrates, eaten at a 250-500 calorie surplus. This calculator builds those exact numbers from your weight and TDEE.
- How much protein do I need to bulk?
- Research supports roughly 0.7-1 gram of protein per pound of body weight per day while gaining muscle. Going much higher offers little extra benefit, so 0.8-1.0 g/lb is the practical target this tool defaults to.
- How many carbs should I eat on a bulk?
- Carbohydrates fill whatever calories remain after protein and fat are set, which on a bulk is usually a large amount. Carbs fuel hard training and recovery, so they should be the biggest macro for most people gaining weight.
- Should fat be higher when bulking?
- Fat is set around 25% of total calories here, which supports hormones without crowding out the carbs that fuel training. You can run a bit higher or lower, but keep fat at least 20% of calories for health.
- Why do my macros not add up to exactly my calories?
- Grams are rounded to whole numbers, so the calorie total can be off by a few. The split is intentionally approximate — total calories drive your gain, so hit your calorie target first and treat the gram targets as guides.