Carpet, built-up or super built-up area: how to measure your flat and what RERA lets you claim if it's short

Rules and rates as of 12 October 2026.

A brochure can describe the same flat with three different numbers: carpet, built-up and super built-up. Only one of them has a legal definition in the Real Estate (Regulation and Development) Act, 2016, and it is the one you can check with a tape measure on the day you take possession.

The three areas, and which one the law recognises

Carpet area is defined in section 2(k) of the RERA Act as the net usable floor area of an apartment, excluding the area covered by the external walls, areas under services shafts, exclusive balcony or verandah area and exclusive open terrace area, but including the area covered by the internal partition walls of the apartment. The Explanation to the clause says a balcony, verandah or open terrace is "exclusive" when it is attached to the flat and meant only for that allottee. Kitchens and toilets are inside the carpet area.

Built-up area and super built-up area (often called "super area" or "saleable area") are not defined in the Act. In common usage, built-up adds the external walls, and often the balconies, to the carpet area. Super built-up goes further and adds a share of the lobbies, staircases, lift wells and sometimes the clubhouse. Because there is no statutory formula, two developers can calculate super built-up very differently.

Term	What it usually adds	Defined in the RERA Act?
Carpet area	Floor inside the flat, including internal partition walls, kitchen and toilets	Yes, s.2(k)
Built-up area	Carpet plus external walls, often balconies	No
Super built-up area	Built-up plus a share of common areas	No

What the Act requires the promoter to do

• Disclose carpet area at registration. Section 4(2) requires the promoter's application to state the number, type and carpet area of apartments for sale. The state RERA portal shows these figures for every registered project.
• Cap the advance. Under section 13(1), a promoter cannot take more than ten per cent of the cost of the apartment before a written agreement for sale is registered. That agreement is where the carpet area and the price are tied together.
• Build to the sanctioned plan. Section 14(1) requires the project to be completed according to the sanctioned plans and specifications. Section 14(2) bars changes to your flat's plan without your prior written consent, except minor changes that an architect or engineer certifies and you are told about. Structural changes are not "minor".
• Make good on other promises. Section 18(3) says that if the promoter fails to discharge any other obligation under the Act, the rules, regulations or the agreement for sale, it is liable to pay compensation. A smaller flat than the agreement promised falls under this provision. Section 12 adds that if you paid money relying on a false statement in an advertisement, prospectus or model flat, you can claim compensation, or withdraw and recover what you paid with interest.

How to measure your flat yourself

1. Get the carpet area from the registered agreement for sale. Do not use the brochure or the payment demand letter. Note whether the figure is in square metres or square feet (1 sq m = 10.7639 sq ft).
2. Measure each room at floor level, from the finished face of one wall to the finished face of the opposite wall, using a laser measure or a steel tape. Include the kitchen, toilets, utility areas inside the flat and the passage.
3. Add the footprint of the internal partition walls. The easiest way is to measure the thickness at a door opening and multiply it by the length of each partition. Leave out the external walls, any duct or shaft, and the balconies and terraces.
4. Write the balcony and terrace areas down separately. They are outside carpet area, but the agreement should list them separately, and you can check those figures too.
5. If the gap matters, have a licensed architect or surveyor measure it again and give you a signed report. A RERA authority will give that report more weight than your own spreadsheet.

Expect a small difference just from plaster, tiles and skirting. A gap of a few square feet is noise. A gap of a few per cent is worth taking up with the promoter.

Worked example: a 650 sq ft flat that measures 626

All figures below are illustrative. Say the agreement records a carpet area of 650 sq ft for a total price of ₹1,04,00,000 (leaving out stamp duty, GST and parking). The brochure quoted a super built-up area of 1,040 sq ft. On possession, your room-by-room measurements total 53.86 sq m, and internal partitions add about 4.30 sq m. That makes 58.16 sq m, or about 626 sq ft.

Item	Formula	Result
Rate per sq ft of carpet	₹1,04,00,000 ÷ 650	₹16,000
Loading factor	Super built-up ÷ carpet = 1,040 ÷ 650	1.60 (60% loading)
Rate per sq ft of super built-up	₹1,04,00,000 ÷ 1,040	₹10,000
Shortfall	650 − 626	24 sq ft
Shortfall as a percentage	24 ÷ 650 × 100	3.69%
Refund at the agreed carpet rate	24 × ₹16,000	₹3,84,000
Interest, if one year at an assumed 11% a year	₹3,84,000 × 11% × 1	₹42,240

Two things stand out. First, the "₹10,000 a sq ft" figure on the super built-up area makes the flat look cheaper, but you are paying ₹16,000 for every square foot you can actually use. Second, the refund has to be worked out at the carpet rate. Pricing the 24 missing sq ft at the super built-up rate would give only ₹2,40,000. The interest rate is a placeholder. Each state's RERA rules set their own rate; Haryana's, for example, is the State Bank of India's highest marginal cost of lending rate plus two per cent (Haryana RERA Rules, 2017, rule 15). Under section 2(za) of the Act, interest on money a promoter owes runs from the date the promoter received it.

Where states differ

Super area as a basis of sale. Haryana's 2017 rules, in rule 4(2) for ongoing projects, require promoters to disclose carpet area "even if sold on any other basis", which accepts that some flats were sold on super area. The HRERA Gurugram (Sale of Apartments/Floors in a Real Estate Project on the basis of Carpet Area) Regulations, 2021 (notified 7 May 2021) go further for projects under that authority. Regulation 5(i) says no apartment shall be sold on any basis other than carpet area. Selling on super area is treated as an unfair practice, conveyance deeds must be registered on carpet area, and for flats already sold on super area the promoter must disclose what made up that super area. So two documents from the same state set different standards, and the stricter one applies only within the Gurugram authority's jurisdiction.

Tolerance bands. The Act itself does not set any permitted percentage of variation. Agreements for sale usually carry their own clause on how the final carpet area is confirmed and how a difference is settled, and state formats differ. Read that clause in your own registered agreement: whether it allows a percentage band, by when a shortfall must be refunded, and at what rate.

If the flat is short

Write to the promoter with your measurement report and the clause number. Ask for the final carpet area certified by the project architect and a refund worked out at the agreed rate. If that fails, section 31 lets any aggrieved allottee file a complaint with the state RERA authority. Claims for compensation under sections 12, 14 and 18 go to the adjudicating officer under section 71. That officer considers, among other factors, any unfair gain the promoter made and the loss you suffered (section 72). A lawyer who practises before your state's RERA can tell you which forum and which relief fit your agreement.