Weight Gain Calculator: How Long to Reach Your Target Weight?
Gaining weight deliberately is just as challenging as losing it. Whether recovering from illness, building muscle, or reversing an underweight status, this calculator gives you a realistic timeline based on your planned daily calorie surplus.
The Formula
kg per week = (Daily Surplus × 7) ÷ 7700
Weeks to goal = Weight to Gain ÷ kg per week
Worked Example
Current: 58 kg. Target: 68 kg. Daily surplus: 400 kcal.
kg/week = (400 × 7) ÷ 7700 = 0.364 kg
Weeks = 10 ÷ 0.364 = ~27.5 weeks (7 months)
Find your timeline with our free Weight Gain Calculator.
Surplus Size vs Quality of Gain
| Daily Surplus | Weekly Gain | Quality |
|---|
| 150–250 kcal/day | 0.14–0.23 kg | Lean gains (with training) |
| 300–500 kcal/day | 0.27–0.45 kg | Moderate pace, some fat gain |
| 700+ kcal/day | 0.64+ kg | Fast but significant fat accumulation |
Practical Tips
Eat calorie-dense whole foods. Nuts, avocado, olive oil, full-fat dairy, and legumes provide concentrated calories without extreme meal volumes.
Eat 4–6 meals per day. Smaller, more frequent meals make high calorie targets easier to achieve than 2–3 large ones.
Add resistance training. Without training, excess calories largely become fat rather than functional muscle.
Track weekly averages. If weight has not changed in 3 weeks, add 100–200 kcal to your daily target.
Final Thoughts
Healthy weight gain takes time and consistency. Hit your calorie target most days, train regularly, and progress will accumulate over months.
Find your personalised timeline with our free Weight Gain Calculator.
If underweight for medical reasons or recovering from an eating disorder, work with a doctor or dietitian for personalised guidance.