The calorie surplus model
Gaining 0.25 kg per week requires a surplus of approximately 1,925 kcal per week (275 kcal/day). The same 7,700 kcal/kg approximation applies here, though during a bulk, not all gained tissue is muscle — some will be fat.
Weight Gain Calculator
Calculate your bulking timeline — see how many weeks to reach your target weight and the daily calorie surplus needed for lean or aggressive muscle gain.
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Units
8 kg
To gain
32
Weeks
275
Daily surplus (kcal)
1925
Weekly surplus (kcal)
| Weight to gain | 8 kg / 17.6 lbs |
| Time to goal | 32 weeks (~7 months) |
| Estimated goal date | October 25, 2026 |
| Daily calorie surplus | 275 kcal/day |
| Weekly calorie surplus | 1925 kcal/week |
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Goal Planning
Weight Gain Calculator
This calculator estimates how long it will take to reach a target weight through a calorie surplus, and shows the daily and weekly surplus needed. It is designed for people looking to gain muscle mass (bulking) or recover from being underweight.
Lean bulk vs. aggressive bulk
A lean bulk (0.125–0.25 kg/week) keeps fat gain minimal and is recommended for most people. An aggressive bulk (0.5–1 kg/week) adds weight faster but most of the excess beyond natural muscle gain rate will be stored as fat. Natural muscle gain is typically limited to 0.25–0.5 kg per week for beginners and much less for advanced trainees.
Maximising muscle gain
For muscle-focused bulking, resistance training and adequate protein intake (1.6–2.2 g per kg of bodyweight per day) are essential. Without a training stimulus, most of the surplus will be stored as fat regardless of the rate.
Frequently asked questions
A small surplus of 200–300 kcal per day above your maintenance calories is generally sufficient for lean muscle gain when combined with resistance training. Larger surpluses primarily add fat.
Most natural beginners can gain 1–2 kg of muscle per month in the first year. Intermediate trainees gain 0.5–1 kg per month, and advanced athletes even less. These rates assume consistent training and adequate nutrition.
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