Calories Intake Calculator

How Many Calories Should You Eat Per Day to Gain/Lose Weight? This is a simple but highly accurate scientific calorie calculator, along with 5 evidence-based tips on how to sustainably reduce calorie intake. Enter your details in the app calculator below to figure out how many calories you should be eating in a day to either maintain, gain or lose weight. The calculator is based on the Mifflin-St Jeor equation, a formula that has been shown to be an accurate way of estimating calorie needs in numerous studies. An average woman needs to eat about 2000 calories per day to maintain, and 1500 calories to lose one pound of weight per week. An average man needs 2500 calories to maintain, and 2000 to lose one pound of weight per week. However, this depends on numerous factors. These include age, height, current weight, activity levels, metabolic health and several others.