Weight Gain Calculator
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Use this Weight Gain Calculator to estimate maintenance calories and a starting daily calorie target for gradual weight gain.
Calculation Method
The calculator first estimates resting calorie needs with the Mifflin–St Jeor equation.
Male: BMR = 9.99 × weight (kg) + 6.25 × height (cm) − 4.92 × age + 5
Female: BMR = 9.99 × weight (kg) + 6.25 × height (cm) − 4.92 × age − 161
Maintenance calories are then estimated as:
TDEE = BMR × activity factor
A calorie surplus based on the selected weekly gain pace is added:
Daily surplus ≈ (planned gain in kg/week × 7,000) ÷ 7
Example
For a 25-year-old male weighing 65 kg, 180 cm tall, with a moderate activity factor of 1.55:
BMR ≈ 1,656 calories/day
TDEE ≈ 1,656 × 1.55 = 2,567 calories/day
For a target gain of 0.5 kg per week, the calculator adds approximately 500 calories per day:
Weight-gain target ≈ 3,067 calories/day
Important Limitations
Calorie needs and weight gain are estimates. Actual changes depend on activity, food intake, muscle and fat gain, genetics, sleep, health, and metabolism.
If you are losing weight unintentionally, are significantly underweight, have difficulty eating enough, or have an eating-disorder history or medical condition, seek professional nutrition or medical guidance rather than relying only on a calculator.