Carpet, Built-Up and Super Built-Up Area Explained
When a builder describes a flat as "1,300 sq ft", that number can mean three different things. Which one is quoted decides how much usable space you get and whether you can fairly compare two projects.
The three measures
| Measure | What it covers | Where the definition comes from |
|---|---|---|
| Carpet area | The net usable floor area inside the flat. | The RERA Act, section 2(k). |
| Built-up area | Carpet area plus the thickness of the walls and usually attached spaces such as a balcony. | Market usage. The RERA Act does not define it. |
| Super built-up area | Built-up area plus the flat's share of common spaces such as lobbies, staircases, lifts and the clubhouse. | Market usage. Each builder calculates it in its own way. |
Banks and property guides describe the second and third measures in much the same way, but they are not legal terms, so two builders can use them differently.
What the law says about carpet area
The Real Estate (Regulation and Development) Act, 2016 defines carpet area as the "net usable floor area of an apartment". The definition leaves out four things: the area under external walls, service shafts, any balcony or verandah meant for your exclusive use, and any exclusive open terrace. It counts the area under the internal partition walls.
That last point matters. Some sellers and older articles describe carpet area as only the space you could cover with a carpet, wall to wall, which leaves out wall thickness. The RERA figure includes internal walls, so it can be a little larger than that older idea of carpet area.
Some further points are worth knowing:
- A promoter registering a project must list the number, type and carpet area of the apartments, along with the exclusive balcony and terrace areas. On the Karnataka RERA portal this appears in the project's development details.
- Karnataka's rules say a promoter of an ongoing project must disclose apartment sizes on the carpet area basis, even where flats were earlier sold on a super area, super built-up or built-up basis.
- Karnataka's prescribed form of agreement for sale, added to the rules in 2020, bases the total price on carpet area and asks for a break-up that includes the exclusive balcony, the share of common areas and preferential location charges. After construction and the occupancy certificate, the promoter must confirm the final carpet area. If it is smaller, the excess money is refunded within 60 days with interest. If it is larger by no more than 3%, the promoter may ask for the extra at the same rate per sq ft.
- Neither the Act nor the rules cap how much common space a builder can add. An Anarock analysis reported by PTI in June 2025 quotes its research head as saying that no law currently limits the loading factor.
What loading is, and how big it gets
Loading is the gap between super built-up area and carpet area, usually written as a percentage of carpet area. If a flat has 1,000 sq ft of carpet area and 1,300 sq ft of super built-up area, the loading is 30%.
There is no official typical figure. An Outlook Money explainer says builders add roughly 20% to 30% over carpet area. The Anarock analysis put Bengaluru's average loading at 41% in the first quarter of 2025, up from 30% in 2019, the biggest rise among the seven large cities it looked at. Treat any average as a rough guide and ask for the number for the flat you are considering.
Worked example: two flats with the same headline size
Both flats below are sold as 1,300 sq ft of super built-up area. The prices are made up to show the method, not to reflect today's market.
| Flat A | Flat B | |
|---|---|---|
| Super built-up area | 1,300 sq ft | 1,300 sq ft |
| Carpet area | 1,000 sq ft | 900 sq ft |
| Loading | 30% | 44% |
| Rate on super built-up area | ₹8,000 per sq ft | ₹7,800 per sq ft |
| Total price | ₹1,04,00,000 | ₹1,01,40,000 |
| Price per carpet sq ft | ₹10,400 | ₹11,267 |
| Carpet area as a share of super built-up | 77% | 69% |
Flat B looks cheaper on both counts: a lower rate per sq ft and a lower total. But you pay about ₹867 more for every sq ft you can actually use, and you get 100 sq ft less of it. Flat A is the better value on this basis, unless something else, such as location, floor or view, outweighs it.
How to compare prices fairly
- Get the RERA carpet area of the exact unit, and the exclusive balcony area separately. The portal shows areas in square metres, and one square metre is about 10.76 sq ft.
- Divide the total price by the carpet area. Make sure both flats are priced on the same inclusions, such as parking, club membership and other charges.
- Work out the carpet share of super built-up area. A lower share means you are paying for more common space.
- Treat the balcony as its own item. It is excluded from carpet area, so compare its size and use separately.
- Compare the unit's carpet area with the figure on the project's RERA page for that apartment type. Check whether the portal figure is per flat or a total for all flats of that type, and divide if needed.
What to ask a builder
- What is the RERA carpet area of this exact flat, and where is it shown on the approved plan?
- Does the agreement state the carpet area, and is the price per sq ft quoted on carpet or super built-up area?
- What is the loading in this project, and which common areas does it cover?
- Does the agreement follow Karnataka's prescribed form, including the clause on the final carpet area? What happens to the price if the measured area differs?
- Does the total include parking, club membership, maintenance deposits and other charges, or are they extra?
- Does the carpet area in the agreement match the project's page on rera.karnataka.gov.in?
Key points
- Carpet area is the only one of the three measures defined in the RERA Act. Built-up and super built-up area are market terms.
- Loading is not capped by law and varies a lot, so ask for it project by project.
- Compare flats by total price divided by carpet area, with the same inclusions on both sides.
- Ask for the carpet and balcony areas in writing and check them against the RERA portal.
Sources
- https://rera.karnataka.gov.in/resources/staticpage/Real_Estate_Act.pdf
- https://dpal.karnataka.gov.in/storage/pdf-files/Kanunu%20padakosha%20PDF%20Files/The%20Karnataka%20Real%20Estate%20(Regulation%20and%20Development)%20Rules,%202017%20(Eng).pdf
- https://dpal.karnataka.gov.in/storage/pdf-files/16of2016RealEstate(regulationDevelopment)(FirstAmendment)Rules2020.pdf
- https://rera.karnataka.gov.in/viewAllProjects
- https://www.outlookmoney.com/explainer/how-is-carpet-area-different-from-super-built-up-area
- https://www.theweek.in/wire-updates/business/2025/06/09/dcm52-biz-realty-housing.html
- https://www.bankbazaar.com/home-loan/resources/carpet-area-vs-built-up-area-vs-super-built-up-area.html
- https://www.icici.bank.in/blogs/home-loan/all-about-carpet-area-built-up-area-and-super-built-up-area.page
This guide is general information, not legal, tax or financial advice. Rules and rates change; check with a lawyer, chartered accountant or your bank before you decide.