RERA Carpet Area vs Super Built-Up: What Mumbai Buyers Pay For

Two brokers showed a Chembur buyer what looked like the same flat at two very different rates per square foot. One quoted 28,000 rupees a square foot, the other 21,000, and the cheaper looking one was actually the costlier home. The difference was not the price, it was the area each was measuring. The lower rate was quoted on super built-up area, a larger number that made the per square foot figure look small, while the higher rate was quoted on carpet area, the space you can actually use. Until you fix the two quotes to the same measure, a per square foot number tells you almost nothing.

The short answer. Carpet area is the net usable floor area inside your flat, and under the Real Estate Regulation and Development Act of 2016 it is the figure builders must disclose and the one you should buy on. Super built-up area adds your share of common spaces like lobbies, lifts and staircases on top, so the same flat can be quoted at a lower rate per square foot on the bigger super built-up number. The trade off is one of clarity, a carpet area rate looks higher but is honest about the space you own, while a super built-up rate looks cheaper but is spread over area you only share. Always compare flats on carpet area.

What exactly is carpet area under RERA?

Carpet area is defined in Section 2(k) of the RERA Act as the net usable floor area of an apartment. It includes the area taken up by the internal partition walls of the flat, and it excludes the area under the external walls, the areas under service shafts, and any exclusive balcony, verandah or open terrace attached to the flat for your use. In plain terms, it is the floor you could actually lay a carpet on, plus the thickness of the inside walls, and nothing beyond the front door.

The reason the definition matters is that it is precise and legally fixed. Before RERA, builders used looser measures that could be stretched, but the Act pinned carpet area to a single meaning so that a buyer in Chembur and a buyer in Thane are measuring the same thing. You can read the statutory definition and a worked example on this explainer of Section 2(k), which sets out exactly what is counted and what is left out.

What is super built-up area, and why is it larger?

Super built-up area is carpet area plus the walls plus a share of the common areas of the building, which makes it the largest of the three common measures. Built-up area is the first step up from carpet, adding the external walls and the balcony, and super built-up goes further by loading on your proportional share of lobbies, staircases, lifts, common basements and similar shared spaces. Because that share is added to every flat, the super built-up figure can be far bigger than the space inside your door.

The gap is called the loading factor, and it is simply the difference between what you pay for and what you can use. A flat with a carpet area that is a large fraction of its super built-up figure has low loading and is efficient, while a flat where carpet is a small fraction of super built-up has high loading. Two towers with the same super built-up rate can therefore give you very different amounts of real living space.

Which number should a Mumbai buyer actually use?

Use carpet area as your anchor, because it is the only measure that describes the home you will live in. Since RERA came into force, the builder must disclose the exact carpet area in the agreement, and the intent of the law is that you buy and pay on carpet area rather than on a notional super built-up figure. When a quote is given on super built-up, ask for the carpet area in writing and recompute the rate per square foot on that smaller number so you can compare like with like.

This single habit protects you from the oldest trick in the quote sheet. A rate that looks low on super built-up can work out more expensive per usable foot than a rate that looks high on carpet. The flat does not change, only the denominator does, and the denominator is where the persuasion hides.

How do balconies and terraces fit in?

An exclusive balcony, verandah or open terrace attached to your flat is left out of the carpet area figure, and the Act requires it to be disclosed separately. That does not mean the space is free, because builders often price it, but it does mean it should appear as its own line rather than being quietly folded into the carpet area. When you see the carpet area, ask what balcony or terrace area goes with it and how that space has been charged.

This separation is useful to you. It lets you see the pure indoor floor on one line and the open space on another, so you can judge each on its merits. A large balcony can be a genuine benefit in Mumbai, but you should know you are paying for it and at what rate, rather than discovering later that it inflated a single blended number.

How does carpet area connect to the MahaRERA listing?

The carpet area is one of the project details a promoter registers with MahaRERA, which gives you an independent place to check the figure. When you verify a project on the regulator's portal, the registered carpet areas and the approved plans are part of what is disclosed, so a figure in a brochure can be checked against a figure on the record. Our guide on how to verify a MahaRERA project registration walks through where to look.

Checking both together is the point. A matching carpet area across the brochure, the agreement and the MahaRERA listing is reassuring, while a mismatch is a question you raise before you pay. The area you are buying should read the same wherever it is written down.

How should you compare two flats on area?

Compare them by reducing both to carpet area and to a true all-in cost. Convert every quote to a rate per carpet square foot, add the state charges on top, and only then rank the options. For a full Mumbai cost picture, pair the area check with our note on stamp duty and registration charges, because the headline rate is only one part of what you finally pay.

What mistakes do buyers make with area figures?

The commonest mistake is comparing a super built-up rate in one project with a carpet rate in another and concluding the first is cheaper. The second mistake is accepting a blended area without asking for the carpet and balcony split, which hides how much usable floor you are really getting. A third is forgetting that the loading factor varies between projects, so two flats with identical super built-up areas can differ in real space by a room's worth.

Avoiding all three comes down to one discipline, insist on the carpet area in writing and do your own per square foot maths on it. The builder's job is to present the flat attractively, and your job is to translate every quote back to the honest measure before you decide. It helps to keep a simple spreadsheet with each shortlisted flat reduced to one column, the price per carpet square foot, because once every option sits in that single honest column the comparison that the quote sheets tried to blur becomes obvious at a glance.

Your carpet area checklist before booking

1. Ask for the exact carpet area of the specific flat, in writing, in square feet.
2. Ask separately for the balcony, verandah or open terrace area attached to the flat.
3. Recompute every quote as a rate per carpet square foot before comparing projects.
4. Check the loading factor by comparing carpet against the super built-up figure.
5. Match the carpet area across the brochure, the agreement and the MahaRERA listing.
6. Confirm how any balcony or terrace area has been priced and on which line.
7. Add stamp duty and registration to the carpet rate for a true all-in cost.

Frequently asked questions

What is the difference between carpet area and super built-up area?

Carpet area is the net usable floor inside your flat, including internal partition walls, while super built-up area adds the walls and your share of common spaces like lobbies, lifts and staircases. Super built-up is always larger, so a rate quoted on it looks lower per square foot. Always compare flats on carpet area.

Does RERA require builders to sell on carpet area?

RERA defines carpet area precisely and requires the promoter to disclose the exact carpet area in the agreement, so the law is built around that figure. The clear intent is that you buy and pay on carpet area. If a quote is given only on super built-up, ask for the carpet area in writing before you decide.

Is balcony area included in RERA carpet area?

No, an exclusive balcony, verandah or open terrace attached to your flat is excluded from the carpet area and must be disclosed separately. That does not make the space free, because builders usually price it, but it should appear on its own line rather than being folded into the carpet figure. Ask how the balcony area has been charged.

What is a loading factor?

The loading factor is the gap between super built-up area and carpet area, representing the share of common spaces added to your flat. A low loading factor means carpet is a large part of super built-up and the flat is efficient, while a high loading factor means more of what you pay for is shared space. Compare loading across projects.

Last updated 2026-10-13. PropNewz Team.