04 June 2026
Carpet, built-up, super built-up: the only area number that should decide your price
Two flats quoted at the same rate per square foot can differ by a fifth in the space you can actually stand in. The loading factor is where that difference hides.
Ask three sellers for the area of a flat and you can get three different numbers for the same flat. None of them is necessarily dishonest. They are measuring different things.
Carpet area is the net usable floor area within the walls of the apartment. Under the RERA definition it excludes the external walls, the areas under service shafts, the exclusive balcony or verandah and the exclusive open terrace, but includes the area covered by the internal partition walls. It is, roughly, the floor you could lay carpet on. It is the number the Act requires a sale to be based on.
Built-up area adds the thickness of the walls and typically the balcony. It generally runs around 10 to 15 per cent above carpet.
Super built-up area, sometimes called saleable area, adds your proportionate share of the common areas — lobbies, staircases, lifts, corridors, the clubhouse, sometimes the plant rooms and the covered parking podium. There is no fixed rule for what a promoter includes, which is precisely why the number varies so much between projects.
The loading factor is the gap between carpet and super built-up, expressed against the carpet. A project at 25% loading gives you 1,000 sq.ft of carpet for 1,250 sq.ft of super built-up. At 40% loading, the same 1,000 sq.ft of carpet is sold as 1,400. If both quote ₹8,000 per square foot on the super built-up number, the second flat costs ₹12 lakh more for identical usable space.
So do the one calculation that compares like with like. Take the total price — all in, including the floor rise, the preferential location charge, parking, club membership and the sinking fund, because those are all really part of the price. Divide it by the carpet area. That is your true rate, and it is the only rate that lets you compare a project with 22% loading against one with 38%.
A high loading factor is not automatically bad. It can mean genuinely large lobbies, wide corridors and a real clubhouse, which you may want. It becomes a problem when it is not disclosed, or when it buys you nothing you will use.
Where to find the real number. For an under-construction unit, the carpet area is in the RERA registration on the state authority's portal and in the agreement for sale. For a completed flat, the approved plan and the agreement of the earlier sale will carry it, and it can be measured. Measuring takes twenty minutes and settles the question.
If a seller will not give you the carpet area in writing, treat that as the answer to a different question.