The price of flats in Kolkata is calculated on the basis of the complete saleable area. We can divide the total cost of a flat into two parts- 1- the carpet area- which is the actual space you will be living in, and 2- the super built-up area. The super built-up area is space within the vicinity which will be regularly used by you such as-the lobby, security rooms, play areas, gyms, staircases, lifts and other common amenities. The price per square feet is calculated with the average super built-up area pertaining to a single buyer ie. The total super built-up area divided by the total number of flats in the residential complex. Thus, the price of a flat = Carpet area + Proportionate super built-up area.