Our calorie calculator estimates your Total Daily Energy Expenditure (TDEE) — the number of calories your body needs each day to maintain your current weight. It uses the Mifflin-St Jeor equation, which is considered the most accurate formula for estimating Basal Metabolic Rate (BMR), and then adjusts for your activity level. To lose weight, you need to consume fewer calories than your TDEE (a deficit of 500 calories per day typically results in about 0.5kg of weight loss per week). To gain weight, you need a calorie surplus. Enter your age, sex, weight, height, and activity level to find your personalised calorie target.