Building healthy weight requires a controlled calorie surplus rather than guesswork. This free online weight gain calculator calculates how much weight you need to gain, your weekly rate of gain, and the daily calorie surplus needed to reach your goal weight in your chosen time frame. It also warns you if your target pace is likely to add excess fat, so you can plan a leaner, more gradual gain.
Find out how much of a daily calorie surplus you need to reach your goal weight in your chosen time frame.
The calculator uses about 7,700 extra kcal per kilogram gained. This is a planning approximation: muscle tissue stores less energy than fat, but building it also uses energy, so actual results vary. The surplus is the number of calories you need to eat above your maintenance level each day. A warning appears if the weekly rate is more than 0.5 kg.
A 55 kg college student wants to reach 60 kg over 20 weeks. That is 5 kg at 5 ÷ 20 = 0.25 kg a week, and a daily surplus of 5 × 7,700 ÷ 140 days = 275 kcal. A glass of milk with a banana, or a handful of peanuts with an evening snack, covers that without forcing large meals.
Trying to gain 6 kg in just 8 weeks means 0.75 kg a week and an 825 kcal daily surplus. The calculator flags this, because at that pace a larger share of the gain is likely to be fat rather than muscle.
| Time frame | Weekly rate | Daily surplus |
|---|---|---|
| 10 weeks | 0.50 kg | 550 kcal |
| 16 weeks | 0.31 kg | 344 kcal |
| 20 weeks | 0.25 kg | 275 kcal |
| 30 weeks | 0.17 kg | 183 kcal |
A surplus of about 250 to 500 kcal a day is a common starting point. Beginners who have just started strength training can usually build muscle faster than experienced lifters, who often do better with a smaller surplus and a slower rate.
People who struggle to gain weight often feel full quickly, so calorie-dense foods and an extra snack work better than simply piling more rice on the plate. Approximate values:
| Food | Energy (approx.) |
|---|---|
| Roasted peanuts, 30 g | 170 kcal |
| Toned milk, 250 ml glass | 145 kcal |
| Banana, 1 medium | 100 kcal |
| Ghee, 1 tablespoon | 120 kcal |
Pair the extra calories with enough protein, roughly 1.6 g per kg of body weight if you are training, from dal, paneer, curd, eggs, chicken or soya. Packaged sweets, fried snacks and sugary drinks do add calories, but they make it more likely that the weight you gain is fat.
A calorie surplus without exercise mostly adds fat. Strength training two to four times a week, such as bodyweight exercises, resistance bands or gym workouts, gives the extra calories a reason to become muscle. Weigh yourself weekly; if your waist is growing much faster than your chest, arms and thighs, reduce the surplus a little.
A BMI below 18.5 is classed as underweight. If you are underweight without an obvious reason, or have lost weight without trying, see a doctor before starting a gain plan: thyroid problems, diabetes, digestive conditions and infections such as tuberculosis can all cause weight loss. This calculator offers general estimates and is not medical advice.