Weight Gain Calculator
Gaining weight in a healthy, controlled manner requires eating more calories than you burn. This calculator estimates your daily calorie target by computing your TDEE and adding the surplus needed to reach your goal weight within your desired timeframe.
Healthy weight gain requires a consistent caloric surplus combined with resistance training to promote lean muscle growth rather than excess fat storage. This calculator uses the Mifflin-St Jeor equation to estimate your Basal Metabolic Rate (BMR), multiplied by your activity factor to determine your Total Daily Energy Expenditure (TDEE). It then calculates the daily caloric surplus needed based on the total weight to gain and your timeframe, using the approximation that 1 kg of body mass requires roughly 7,700 excess calories.
For lean muscle gain, a surplus of 250–500 calories per day (about 0.25–0.5 kg per week) is generally recommended, as larger surpluses tend to produce more fat gain. Protein intake of 1.6–2.2 g per kg of body weight supports muscle protein synthesis. Always consult a healthcare professional or registered dietitian for personalized advice, especially if you are underweight or recovering from illness.