Weight Gain Calculator

The calculator first estimates your Total Daily Energy Expenditure (TDEE) using the Mifflin-St Jeor equation, which calculates your Basal Metabolic Rate (BMR) based on your weight, height, age, and biological sex. For males, BMR is calculated as (10 * weight in kg) + (6.25 * height in cm) - (5 * age) + 5, while for females, it subtracts 161 instead of adding 5. This baseline is then multiplied by your specific activity factor to find your maintenance calories. To achieve a surplus, additional calories are added depending on your chosen weight gain pace.

Let us walk through a practical example for a 25-year-old male who is 175 cm tall, weighs 65 kg, and has a moderately active lifestyle with an activity factor of 1.55. First, his BMR is calculated: (10 * 65) + (6.25 * 175) - (5 * 25) + 5 = 650 + 1093.75 - 125 + 5 = 1623.75 calories per day. Multiplying this by his activity factor of 1.55 gives a maintenance level of approximately 2,517 calories. To gain weight at a healthy pace of 0.5 kg per week, an additional surplus of 500 calories is added, resulting in a target daily intake of roughly 3,017 calories.

Focus on nutrient-dense, calorie-rich whole foods such as nuts, avocados, lean proteins, and complex carbohydrates rather than empty sugars. Combine your caloric surplus with a structured resistance training program to ensure that the weight you gain is primarily muscle mass rather than unwanted fat. Monitor your progress weekly and adjust your calorie intake upwards if your weight plateaus for more than two consecutive weeks.