Gaining weight slowly, at about 0.25–0.5 kg (0.5–1 lb) a week, with resistance training and enough protein, helps more of the gain be muscle. Faster gains are mostly fat.
How to use the Weight Gain Calculator
- Sex
- Age
- Weight
- Height
- Activity level
- Goal weight
- Weekly weight gain
Results update as you type, and every field accepts the units shown in its menu.
How it works
Enter your details, activity level, goal weight and weekly gain. The calculator finds your TDEE with Mifflin–St Jeor, adds the surplus and divides the total gain by your weekly rate.
Inputs explained
| Field | What to enter |
|---|---|
| Sex | Choose one: Male, Female |
| Age | In years |
| Weight | Units: kg, lb, st, g |
| Height | Units: cm, in, m, ft, mm |
| Activity level | Choose one: Basal metabolic rate (no activity), Sedentary – little or no exercise, Light – exercise 1–3 times a week, Moderate – exercise 4–5 times a week … |
| Goal weight | Units: kg, lb, st, g |
| Weekly weight gain | Units: kg, lb, st, g |
What each result means
- Daily calories to gain weight = [Maintenance calories] + [Weekly weight gain]×7700÷7
- Daily surplus = [Weekly weight gain]×7700÷7
- Time to reach your goal = ([Goal weight] – [Weight])÷[Weekly weight gain]
- Protein to support muscle (1.6 g/kg) = 1.6×[Weight]
Example values
How the main result changes when Age changes and everything else stays at the example values above:
| Age (years) | Daily calories to gain weight (kcal/day) |
|---|---|
| 15 | 2,901 |
| 22.5 | 2,846 |
| 30 | 2,791 |
| 37.5 | 2,736 |
| 45 | 2,681 |
| 60 | 2,571 |
Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.
Formula
Daily surplus = weekly gain × 7,700 kcal/kg ÷ 7
Intake = TDEE + surplus
Weeks = (goal − current) ÷ weekly gain
Worked example
Inputs — Sex: Male; Age: 30 years; Weight: 75 kg; Height: 178 cm; Activity level: Moderate – exercise 4–5 times a week; Goal weight: 82 kg; Weekly weight gain: 0.25 kg.
Results — Maintenance calories = 2,516 kcal/day; Daily calories to gain weight = 2,791 kcal/day; Daily surplus = 275 kcal/day; Time to reach your goal = 28 weeks; Protein to support muscle (1.6 g/kg) = 120 g/day.
Key terms
- Calorie surplus
- Eating more calories than you burn.
Frequently asked questions
How fast should I gain weight?
About 0.25–0.5 kg (0.5–1 lb) a week for lean gains.
What should I eat?
Energy-dense whole foods: nuts, dairy, whole grains, olive oil, eggs, meat or legumes.
Why am I not gaining?
Your activity may be higher than you think; add 200–300 kcal and reassess.
Sources
- Mifflin MD et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr, 1990
- Roza AM, Shizgal HM. The Harris Benedict equation reevaluated. Am J Clin Nutr, 1984
- McArdle WD, Katch FI, Katch VL. Exercise Physiology: Nutrition, Energy and Human Performance