Lifesum's calculations are based on the Mifflin - St Jeor equation. This equation is used in clinical settings to determine patients' caloric needs based on their basal metabolic rate (BMR) and activity level. Since it is the most reliable method to calculate with the user information we have we have decided to use it for our calculations:
BMR = 10 * weight(kg) + 6.25 * height(cm) - 5 * age(y) + 5 (man)
BMR = 10 * weight(kg) + 6.25 * height(cm) - 5 * age(y) - 161 (woman)
The calorie goal is calculated depending on the the plan the user is choosing (gain, lose, maintain/be healthy).
Please note that adding a partner like Jawbone, Fitbit etc will automatically reduce the calorie goal as you will earn extra calories through movement during the day and thus be able to consume more again.