A couple comparing two Bengaluru flats found a puzzle. One was quoted at a lower price per square foot than the other, yet when they walked both homes, the cheaper one felt distinctly smaller inside. The answer sat in a word most brochures use loosely: area. One builder was quoting super built-up area, the other was closer to carpet area, and the same rupees bought very different living space. Learning to read these three terms, carpet, built-up, and super built-up, is how you compare flats honestly rather than being dazzled by a headline rate. This guide explains each and shows you what you actually pay for.

The short answer. Carpet area is the net usable floor space inside your flat, the area you can actually lay a carpet on. Built-up area adds the thickness of walls and some attached spaces, and super built-up area adds a share of common areas like lobbies, staircases, and amenities. Under the national real estate law, builders are required to price and sell on carpet area, which is the transparent number to compare. The trade off to understand is that a low price per square foot quoted on super built-up area can cost more per usable square foot than a higher rate quoted on carpet area, so always compare like with like.

What is carpet area, and why does it matter?

Carpet area is the net usable floor area of your apartment, and it is the number that reflects the space you will actually live in. Under the definition set by the national real estate law, carpet area is the net usable floor area of an apartment, excluding the area covered by the external walls, areas under service shafts, the exclusive balcony or verandah area, and the exclusive open terrace area, but including the area covered by the internal partition walls of the apartment. In plain terms, it is the floor inside your walls, counting the internal partitions but not the external walls, shafts, or your balcony. For a buyer, carpet area matters because it is the honest measure of how much home you are getting, and comparing two flats on carpet area is the only way to know which genuinely gives you more room.

The reason this deserves attention is that living space, not signage, is what you occupy every day. Two flats can be marketed at the same size on a glossy sheet, yet differ in real usable area once you strip out the common spaces bundled into a super built-up figure. Anchoring on carpet area keeps your comparison grounded in what you can actually use.

There is a simple mental test that helps. When a salesperson quotes a size, ask yourself whether that number is space you could furnish or space you merely share with the whole building. A wide marble lobby is pleasant, but you cannot put a bed in it. Carpet area answers the furnishing question directly, which is why it deserves to be the first figure you write down for every flat, before the rate, before the floor, and before the view.

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

The three terms describe progressively larger measures of the same flat. Carpet area is the usable space inside, built-up area adds the walls and certain attached spaces, and super built-up area adds a proportionate share of the building's common areas and amenities. According to Godrej Properties' explainer on carpet area, built-up area typically exceeds carpet area by around 10 to 20 percent, and super built-up area usually exceeds built-up area by a further 25 to 30 percent, with carpet area often working out to roughly 70 percent of the built-up space. The table below lays out the three side by side.

What is the loading factor, and why do some rates look cheaper?

The loading factor is the gap between super built-up area and carpet area, expressed as a proportion of the carpet area. If a flat has a carpet area of 1,000 square feet and is sold as 1,400 square feet of super built-up area, the loading is 40 percent. Loading varies widely between projects, commonly running from around 25 percent to over 40 percent, depending on how generous the shared amenities are. This is why a rate that looks cheap per square foot can be misleading: a low rate applied to a heavily loaded super built-up figure can work out to more per usable square foot than a higher rate applied to carpet area. The way to see through it is to divide the total price by the carpet area for each option, which gives you a true cost per usable square foot to compare.

Amenities are not free, and a higher loading is not automatically bad. A project with a large clubhouse, wide lobbies, and generous landscaping loads those costs across its flats, and some buyers happily pay for them. The point is not to avoid loading, but to see it clearly, so you are choosing to pay for shared spaces rather than mistaking them for private ones.

Two flats with the same super built-up size can hide very different carpet areas if their loading factors differ, which is exactly how a home that looks identical on paper can feel smaller in person. This is why the loading factor deserves a line in your comparison sheet next to the price. A modest difference in loading, applied to a large purchase, can amount to a room's worth of usable space that you either gain or quietly give up without noticing.

Does the law require builders to sell on carpet area?

Yes, under the national real estate law, builders are required to base their pricing and sale on the carpet area rather than the super built-up area. This provision was introduced to end a long standing confusion, where prices were quoted on inflated super built-up figures that bundled in non usable spaces. For a buyer, the practical effect is that the sale documents for a regulated project should state the carpet area clearly, and you are entitled to see it. If a sales conversation drifts back to super built-up area, steer it back and ask for the carpet area in writing, since that is the figure the law expects to govern your purchase and the one that lets you compare flats fairly.

How should you use these numbers when comparing flats?

Use carpet area as your common yardstick, and convert every quote back to it before you compare. Ask each builder for the carpet area and the super built-up area, work out the loading, and divide the total price by the carpet area to get a true cost per usable square foot. Then set that against the rest of your buying maths, because the space you are buying and the charges you will pay on it go together. Our guide to stamp duty and registration charges for Bengaluru buyers covers those statutory costs, and if you are buying a new project, our note on how to verify a RERA registration in Bengaluru shows where to find the project's declared details. When you tour a launch such as Lodha at Sadahalli, ask for the carpet area of the specific unit rather than the tower's headline size.

Carrying this habit through your whole search pays off. Once you train yourself to ask for carpet area first, the comparisons become simple, and the flat that felt bigger on a walk through usually turns out to be the one with the larger carpet area, exactly as your instinct suggested.

A seven step checklist for comparing area before you buy

Run through these steps for every flat you seriously consider.

1. Ask for the carpet area of the specific unit, in writing, not just the tower's headline size.
2. Ask for the super built-up area too, so you can see the loading.
3. Calculate the loading factor as the gap between super built-up and carpet, over carpet area.
4. Divide the total price by the carpet area to get the true cost per usable square foot.
5. Compare flats on that cost per usable square foot rather than the headline rate.
6. Confirm the sale documents state the carpet area clearly for the regulated project.
7. Decide consciously whether the amenities behind a higher loading are worth it to you.

Common questions from Bengaluru buyers

What is carpet area under RERA?

Carpet area is the net usable floor area of an apartment. Under the national real estate law it excludes external walls, service shafts, the exclusive balcony or verandah, and the exclusive open terrace, but it includes the internal partition walls. It is the space you can actually use inside your flat, and the fair basis for comparing homes.

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

Built-up area is the carpet area plus the walls and certain attached spaces, typically 10 to 20 percent above carpet area. Super built-up area adds a proportionate share of common areas such as lobbies and amenities, usually 25 to 30 percent above built-up area. Super built-up is the largest figure and the least useful for comparison.

What is a loading factor in a flat?

The loading factor is the difference between the super built-up area and the carpet area, expressed as a share of the carpet area. If a 1,000 square foot carpet flat is sold as 1,400 square feet, the loading is 40 percent. Loading commonly ranges from about 25 percent to over 40 percent between projects.

Do builders have to sell on carpet area?

Yes, under the national real estate law, builders are required to price and sell regulated projects on carpet area rather than super built-up area. This was introduced to stop prices being quoted on inflated figures. Ask for the carpet area in writing, since it is the number the law expects to govern your purchase.

Last updated 2026-07-21. PropNewz Team.