The definition, in plain words
RERA's section 2(k) defines carpet area as the usable floor inside your flat. It counts internal partition walls. It leaves out external walls, service shafts, and your exclusive balcony, verandah or open terrace.
Built-up area
Built-up area adds the thickness of the walls to carpet area, and some builders add the balcony too. There is no single rule, so the same flat can have different built-up figures from different people.
Super built-up area
Super built-up area goes further, adding a share of the common areas. Each project chooses its own method. That is why one builder's 1,300 sq ft and another's may hide very different homes.
One flat, three numbers
Picture a 2 BHK with these figures:
- Carpet area: 850 sq ft.
- Built-up area (with walls and balcony): about 1,000 sq ft.
- Super built-up area (with a share of common areas): about 1,150 sq ft.
Same home. If two projects each quote ₹80 lakh, but one means 850 sq ft carpet and the other 850 sq ft super built-up, the second flat has noticeably less usable space for the same money.
Where each number fits
- Carpet area: the agreement and price. Compare on this.
- Built-up: useful for an architect or interior designer.
- Super built-up: sometimes used for maintenance charges. Ask how they are calculated.
What goes in the agreement
Your agreement for sale should state carpet area. Balcony and terrace areas, if any, should be listed separately.
Comparing two projects
Square metres and square feet
Some documents give area in square metres. One square metre is about 10.764 sq ft. So a carpet area of 79 sq m is about 79 × 10.764 = 850 sq ft. Keep a calculator handy when you read an agreement, because one document may use metres and another feet.
Worked example: the "loading" trap
Illustrative figures only. "Loading" is the extra area added on top of carpet area to reach super built-up area. You can work it out yourself:
Loading % = (super built-up − carpet) ÷ carpet × 100
Now compare two flats a first-home buyer might see in a week:
| Flat X | Flat Y | |
|---|---|---|
| Quoted area (super built-up) | 1,200 sq ft | 1,200 sq ft |
| Carpet area (from the agreement) | 900 sq ft | 800 sq ft |
| Loading | (1,200 − 900) ÷ 900 = 33% | (1,200 − 800) ÷ 800 = 50% |
| Total cost | ₹72 lakh | ₹68 lakh |
| Cost per sq ft of carpet | ₹72,00,000 ÷ 900 = ₹8,000 | ₹68,00,000 ÷ 800 = ₹8,500 |
Flat Y looks ₹4 lakh cheaper. But per square foot you can actually use, it costs ₹500 more. And you get 100 sq ft less floor inside your walls, roughly the size of a small bedroom.
Step by step: compare any two flats in ten minutes
- Ask for the carpet area of the exact unit, in writing. Not "about", not "typical".
- Ask for balcony and terrace areas separately.
- Ask for the total cost with every charge: base price, parking, GST, club or amenity charges, maintenance deposit.
- Divide total cost by carpet area for each flat.
- Work out the loading if you have been given a super built-up figure.
- Visit the sample flat with a tape measure and check one or two rooms against the plan.
- Only then compare EMIs and decide.
What the cost per square foot does not show
Carpet area tells you how much floor you get. It does not tell you how well that floor is used. Two 800 sq ft flats can feel very different. Check:
- Room shapes. Square-ish rooms are easier to furnish than long, narrow ones.
- Corridor space. A long passage inside the flat counts as carpet area, but you cannot put a bed in it.
- Wall space for furniture. Too many doors and windows on one wall can make a room hard to use.
- Light and air. Windows on two sides of a flat help with cross-ventilation.
Common mistakes first-time buyers make
- Comparing price per sq ft of super built-up area. It mixes in common areas that each builder measures differently.
- Not asking about balconies. Under section 2(k) of RERA, exclusive balconies are outside carpet area. Make sure they are listed separately and not quietly added to the carpet figure.
- Forgetting maintenance. If maintenance is charged per sq ft of super built-up area, a high loading means a higher bill every month for as long as you live there.
- Trusting a brochure over the agreement. The agreement for sale is what binds the builder. Check the area there.
What to do if the area is short
Because the agreement states carpet area, you have something definite to measure against at handover. If the flat you receive does not match what was agreed, raise it in writing before you accept possession, and take advice on your options under RERA.
Worked example: what loading does to your maintenance bill
Illustrative figures only. Suppose both flats in the table above are charged maintenance at ₹4 per sq ft of super built-up area each month. Both have 1,200 sq ft super built-up, so both pay 1,200 × ₹4 = ₹4,800 a month. But Flat X gives you 900 sq ft of carpet and Flat Y gives you 800. Per square foot of usable space, Flat X pays ₹4,800 ÷ 900 = about ₹5.33, and Flat Y pays ₹4,800 ÷ 800 = ₹6. Over ten years, at the same rate, each flat pays ₹5.76 lakh in maintenance, but Flat Y's owner gets less home for it.
Some associations charge on carpet area instead, which is fairer to compare. Ask which method will be used, and ask for it in writing.
A short checklist to take to every site visit
- Carpet area of this exact unit, in writing.
- Balcony and terrace areas, listed separately.
- Super built-up area, if quoted, and the loading worked out.
- Total cost, with every charge listed.
- Cost per sq ft of carpet area, worked out by you.
- How maintenance will be charged, and at what rate to start.
- A tape-measure check of at least one room in the sample flat.
Keep the answers for each flat on one page. When you sit down to decide, you will be comparing like with like.
Putting it together with your loan
Illustrative figures only. If you borrow 80% of Flat X's ₹72 lakh, the loan is ₹57.6 lakh. For Flat Y's ₹68 lakh, it is ₹54.4 lakh. Flat Y's EMI is lower, but you are paying it for less usable home. The fair question is not "which EMI is smaller?" but "which flat gives me the space I need at a cost per square foot of carpet I can carry?". Answer that first, and the EMI comparison becomes meaningful.
Divide each flat's total cost by its carpet area. That gives a fair cost per square foot of usable space. Do the same for the EMI: our EMI calculator shows what each option costs you per month.
What to ask for
- Carpet area of the exact flat, in writing.
- The total cost, with every charge listed.
- How maintenance charges will be calculated.