Carpet Area vs Built Up Area vs Super Built Up Area: A Bangalore Guide

A brochure says 1,450 sq ft. You walk in, and the flat feels closer to 1,050. Nobody lied, exactly. They just quoted a different number from the one you live in. Understanding carpet area vs built up area vs super built up area is the single easiest way to compare Bangalore projects fairly and avoid overpaying for corridors and clubhouse space you never use.

This guide explains each measurement, how the RERA Act defines carpet area, what a typical loading looks like in Bangalore right now, and how to turn a builder's per-sq-ft rate into what you are really paying.

Carpet area vs built up area vs super built up area at a glance

• Carpet area: the usable floor area inside your flat, the space you could actually lay a carpet on, including internal walls.
• Built-up area: carpet area plus the thickness of the external walls, plus exclusive balconies, utility areas and shafts attached to your flat.
• Super built-up area (SBA): built-up area plus your proportionate share of common areas such as lobbies, staircases, lift wells, corridors, the clubhouse and sometimes the gym, pool deck and security cabin.

Every flat therefore has three honest numbers, and they always run in this order: carpet is smallest, super built-up is largest. The gap between them is where buyers get confused.

How RERA defines carpet area

Section 2(k) of the Real Estate (Regulation and Development) Act, 2016 defines carpet area as the net usable floor area of an apartment, excluding the area covered by the external walls, areas under service shafts, exclusive balcony or verandah area and exclusive open terrace area, but including the area covered by the internal partition walls of the apartment.

Two details matter here. First, balconies and private terraces are not part of RERA carpet area, even though you use them. Good builders list them separately in the agreement. Second, internal walls are included, so a flat with many small rooms can show a slightly higher carpet area than its open floor space suggests.

Since RERA came in, registered projects must disclose carpet area in the agreement for sale and on the RERA Karnataka project page. Many Bangalore developers still advertise in super built-up terms, because that is how the market has always quoted. That is not illegal by itself, but the carpet figure should be written down somewhere you can check.

Built-up area: the number in between

Built-up area has no single statutory definition, which is why you will see it calculated slightly differently from builder to builder. In practice it usually adds roughly 10 to 15 percent on top of carpet area, depending on wall thickness, balcony size and whether utility and duct spaces are counted.

For a resale flat in an older Bangalore building, the sale deed may mention only built-up or super built-up area. In that case, measure the rooms yourself or ask for the approved floor plan, so you know what you are buying.

Loading factor in Bangalore: how much is common area?

The loading factor is how much the super built-up area is inflated over carpet area. Different people express it two ways, so always ask which one a sales team means:

• Loading on carpet: (SBA minus carpet) divided by carpet. A 1,000 sq ft carpet flat sold as 1,300 sq ft SBA has 30 percent loading.
• Common area as a share of SBA: (SBA minus carpet) divided by SBA. The same flat has about 23 percent of its SBA in common areas.

For years, Bangalore apartments sat at roughly 25 to 30 percent loading. That has crept up. ANAROCK's research put Bengaluru's average loading at about 30 percent in 2019 and around 41 percent in early 2025, driven by bigger clubhouses, wider lobbies and more amenity space. Treat these as market averages, not rules. A compact mid-rise project in Banashankari can be far lower than a high-rise township on Sarjapur Road with a 40,000 sq ft clubhouse.

Higher loading is not automatically bad. You may genuinely value the pool and co-working lounge. The point is to know what you are paying for, and to compare projects on carpet area, not SBA.

Worked example: converting super built-up to carpet area

Say a project in Thanisandra quotes a 3 BHK at 1,500 sq ft super built-up for ₹9,000 per sq ft. The sales team confirms loading is 35 percent on carpet.

1. Total base price: 1,500 x ₹9,000 = ₹1.35 crore (before GST, parking, maintenance deposit and other charges).
2. Carpet area: 1,500 divided by 1.35 = roughly 1,111 sq ft.
3. Effective rate on carpet: ₹1.35 crore divided by 1,111 = roughly ₹12,150 per sq ft.

Now compare a second project nearby at 1,450 sq ft SBA for ₹8,700 per sq ft, with a stated carpet area of 1,160 sq ft. Its base price is about ₹1.26 crore, and its effective carpet rate works out to roughly ₹10,875 per sq ft. On the brochure, the first flat looked bigger. In real living space, the second one is larger and cheaper per usable foot.

This one calculation is why we always tell buyers to build a simple sheet with carpet area and all-in price for every shortlisted flat.

How builders quote prices, and what to watch for

• Per sq ft on SBA: still the most common way Bangalore projects advertise. Easy to compare across ads, but misleading on space.
• Per sq ft on carpet: required to be disclosed in RERA documents. The rate looks higher because the denominator is smaller.
• Lump-sum unit price: increasingly common. Good, as long as the carpet area is stated alongside it.
• Add-ons: car parking, clubhouse membership, BESCOM and BWSSB deposits, legal fees and corpus fund are often quoted separately. Our guide on hidden costs of buying a flat covers these in detail.

Be careful with phrases like "saleable area" or "chargeable area". They usually mean super built-up area. Ask for the carpet figure in writing.

What to check in the sale agreement

• The RERA carpet area of the flat, stated as a number, plus exclusive balcony and terrace areas listed separately.
• A floor plan with dimensions attached as a schedule, matching the plan uploaded on RERA Karnataka.
• The area variation clause. RERA-format agreements generally say the final carpet area will be confirmed after the occupancy certificate. If it shrinks, the excess paid should be refunded. Extra charges for an increase are typically capped at around 3 percent. Read your own clause carefully, since wording varies.
• Whether the price is linked to carpet area, SBA or a lump sum, and how GST is applied.
• Your undivided share of land (UDS), explained below.

UDS: the land share most buyers forget

When you buy an apartment, you also buy an undivided share of the land the building stands on. You cannot fence it off, but it is legally yours and matters if the building is ever redeveloped.

In Karnataka, apartment ownership works under the Karnataka Apartment Ownership Act, 1972. The builder registers a deed of declaration that describes the building and fixes each flat's undivided share. UDS is usually allotted in proportion to your SBA compared to the total SBA of the project. So a flat with high loading may get a slightly larger land share, which is one small benefit of paying for common area.

Check that the UDS is written in the sale deed in sq ft, and that it is consistent with the deed of declaration. If a builder adds towers or floors later, the land share per flat can shrink, so a stated UDS protects you. A property lawyer can check that the total UDS across all flats does not exceed the land actually owned.

If you are comparing two or three projects and the numbers do not line up, Skyros Estates can help you shortlist, line up site visits and check the carpet area and UDS details in the paperwork before you commit.