Two buyers compared flats in Bengaluru in 2026, both advertised as 1,300 square feet at a similar price per square foot, and assumed they were getting the same home. They were not. One flat had a carpet area of 1,000 square feet; the other, sold by a builder with a heavier loading factor, gave barely 900 square feet of usable space for the same headline size. The difference was 100 square feet of a home they would live in every day, hidden inside a number that looked identical on both brochures.

Carpet area, built-up area and super built-up area are three different numbers for the same flat, and confusing them is how buyers overpay for space they never actually get. Here is what each means, what the loading factor does to your money, and why RERA now puts carpet area at the centre.

The short answer. Carpet area is the net usable space within your walls, built-up area adds the walls and balcony, and super built-up area adds your share of common areas like lobbies and staircases. The gap between super built-up and carpet is the loading factor, often 20 to 35 percent, and you pay for all of it while living in only the carpet area. RERA now requires builders to sell and disclose on carpet area, as guides like this area explainer confirm. The trade-off to grasp: two flats at the same super built-up size and price can give very different usable space, so always compare on carpet area.

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

They are three concentric measurements of the same flat, each larger than the last. Carpet area is the actual usable floor area within the walls of your flat, the space you could literally lay a carpet on. It is the number that determines how much room you really have.

Built-up area is larger, because it adds the thickness of the walls and the balcony to the carpet area, and it is typically 10 to 20 percent more than carpet. Super built-up area is larger still, because on top of the built-up area it adds your proportionate share of the building's common spaces, such as the lobby, corridors, staircases and lift areas. Historically, builders quoted super built-up area because it makes a flat sound bigger, even though you cannot live in a staircase. Knowing which number you are being quoted is the first step to comparing flats honestly.

What is the loading factor and why does it matter?

The loading factor is the gap between the super built-up area and the carpet area, expressed as a percentage, and it is where a lot of buyer money quietly goes. If your carpet area is 1,000 square feet and the loading factor is 25 percent, the super built-up area becomes 1,250 square feet. That extra 250 square feet is not usable space inside your flat; it is your share of common areas, and you pay for it.

This matters because price is usually quoted per square foot of super built-up area. A higher loading factor makes a flat look bigger and lets a builder present a lower per-square-foot rate, while you actually get less usable space. Two flats can have the same carpet area, but the one with the heavier loading will show a larger super built-up size and cost you more in total. When you divide the total price by the carpet area, rather than the super built-up area, you see the true rate for the space you will actually use, and that is the number to compare across projects.

A quick comparison makes the trap obvious. Say two flats both quote 1,300 square feet super built-up at 8,000 rupees per square foot, so both cost about 1.04 crore. Flat A has a 20 percent loading, giving roughly 1,083 square feet of carpet. Flat B has a 35 percent loading, giving only about 963 square feet of carpet. You pay the same 1.04 crore for both, but Flat A hands you 120 square feet more of the space you actually live in. On the carpet area that matters, Flat A costs about 9,600 rupees a square foot and Flat B about 10,800, even though their brochures showed the identical rate.

The three areas at a glance

The table below sets out what each term includes and what it means for you as a buyer.

The bottom two rows are the ones that protect your wallet. A high loading factor is not illegal, but it is money you spend on space you do not live in, and RERA's carpet-area rule exists precisely so you can see through the bigger number.

What does RERA say about carpet area?

RERA made carpet area the mandatory basis for selling and disclosing a flat. Before RERA, builders routinely quoted only super built-up area, which let two flats with very different usable space look similar on paper. Now a builder must clearly state the carpet area in the agreement and cannot sell you a flat solely on an inflated super built-up figure.

For a buyer this is a powerful protection, but only if you use it. Read the carpet area in your agreement, not just the super built-up number in the brochure, and base your price comparison on it. The loading factor and super built-up area still exist and still affect your total cost, but RERA guarantees you the one number that reflects the home you will actually occupy. Insist on seeing it in writing before you compare or commit.

How should I compare flats on the right area?

Compare like with like, always on carpet area. Work through this sequence when you evaluate any flat:

1. Ask for the carpet area in square feet, and confirm it appears in the agreement, not just the brochure.
2. Ask for the super built-up area too, and calculate the loading factor between the two.
3. Divide the total price by the carpet area to find the true rate for usable space.
4. Compare that carpet-based rate across projects, rather than the quoted super built-up rate.
5. Be wary of a very low headline rate, which often hides a high loading factor.
6. Visit the flat and sense-check that the usable space matches the carpet area stated.
7. Confirm the carpet area you are paying for matches what is finally built at possession.

This comparison ties into your wider checks. RERA's carpet-area rule is one of the protections we cover in our guide to verifying a K-RERA registration, and confirming the delivered carpet area is part of the inspection in our flat possession and snagging checklist. If you are comparing a project such as Sobha Neopolis in Panathur, ask for its carpet area and loading factor before you judge the price.

What mistakes do buyers make with area?

The biggest mistake is comparing flats on the super built-up rate without checking the loading factor, so a flat that looks cheaper per square foot actually delivers less usable space. The second is reading only the brochure's super built-up number and never checking the carpet area written into the agreement.

The third mistake is being impressed by a large super built-up size without asking how much of it is common area you cannot use. The fourth is forgetting to confirm, at possession, that the carpet area delivered matches what you paid for. Always ask for the carpet area, compute the loading factor, price the home on carpet, and treat the super built-up figure as marketing rather than the measure of your home.

None of this means a high loading factor is automatically a bad deal. A project with generous lobbies, wide corridors and rich amenities genuinely uses more common area, and some buyers happily pay for that. The point is not to avoid loading, but to see it clearly and decide knowingly, rather than discovering after you move in that a chunk of the square footage you paid for is corridor and clubhouse. Priced on carpet, you can weigh a spacious-amenity project against a leaner one on equal terms and pick what genuinely suits your needs and budget.

Frequently asked questions

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

Carpet area is the net usable floor space within your walls, where you actually live. Super built-up area is larger because it adds the walls, balcony and your proportionate share of common areas like lobbies and staircases. The difference between the two is the loading factor, which you pay for even though it is not usable space inside your flat.

What is a loading factor?

The loading factor is the percentage gap between the super built-up area and the carpet area. If your carpet area is 1,000 square feet and the loading factor is 25 percent, the super built-up area is 1,250 square feet. That extra 250 square feet is your share of common areas, which you pay for but cannot live in.

Does RERA require selling on carpet area?

Yes. RERA requires builders to sell and disclose flats on the basis of carpet area, and to state it clearly in the agreement. Before RERA, builders often quoted only super built-up area, which could mislead buyers. Now you have a right to the carpet area figure, so always read it in the agreement and compare flats on that number.

Should I compare flats on carpet area or super built-up area?

Always on carpet area. Divide the total price by the carpet area to find the true rate for the space you will actually use, and compare that across projects. Comparing on super built-up area can make a flat with a high loading factor look cheaper per square foot while giving you less usable space for your money.

Last updated 2026-08-22. PropNewz Team.