The Calorie Surplus Calculator helps you determine how many extra calories you need each day to gain weight safely and effectively. By entering your age, height, weight, gender, and activity level, this tool estimates your Basal Metabolic Rate (BMR) using the Mifflin–St Jeor formula and calculates your Total Daily Energy Expenditure (TDEE). You can then set a target weight gain rate (for example, 0.25–1 kg per week) to find out your required daily calorie surplus. The calculator supports both metric and imperial units and is fully mobile-friendly and WordPress-compatible. It’s ideal for people who want to build muscle or increase body mass in a controlled, healthy way. However, results are only estimates — for personalized nutrition plans, always consult a certified dietitian or healthcare professional.