Carpet Area vs Built-Up vs Super Built-Up: What You're Really Paying For in a Mumbai Flat
RERA carpet area is the usable floor area inside your walls, excluding external walls, balconies and terraces. How it differs from built-up area, and how to check it.
Two flats are both advertised as "1,000 sq ft". One feels spacious, the other cramped. The difference is almost always which "sq ft" the number refers to. Under RERA, there's only one that should matter to you: carpet area.
What is carpet area under RERA?
Section 2(k) of the Real Estate (Regulation and Development) Act defines carpet area as the net usable floor area of an apartment. As summarised in a CaseMine legal column:
- Excluded: area under external walls, service shafts, exclusive balcony or verandah, and exclusive open terrace.
- Included: area under internal partition walls.
Balconies and terraces are disclosed separately in project registration documents.
What is the difference between carpet, built-up and super built-up area?
| Term | Roughly what it includes |
|---|---|
| Carpet area (RERA) | Usable floor area inside the flat, including internal walls |
| Built-up area | Carpet area plus external walls, and often balconies |
| Super built-up area | Built-up area plus a share of lobbies, lifts, staircases and amenities |
Built-up and super built-up are market terms, not RERA definitions, and different developers calculate them differently. That's exactly why the carpet area is the number to compare.
How do I convert carpet area from square metres?
MahaRERA documents often show areas in square metres. One square metre is 10.764 sq ft. So 65 sq m is about 700 sq ft, and 70.9 sq m is about 763 sq ft.
Compare flats on carpet area, always. Every other number is a story someone is telling you.
How to check the carpet area of a flat in Mumbai
- Read the agreement: it should state the RERA carpet area, with balcony and terrace areas separately.
- Match the approved plan: since 12 October 2026, Maharashtra sub-registrars must refuse registration if the deed area is larger than the approved plan. See our post on the new registration rules.
- Measure on site with a laser measure, room by room. Small differences are normal; large ones are a question for the developer.
- Compare price per carpet sq ft across projects, not price per super built-up sq ft.
What this means for you
- Buyers: ask every seller for the carpet area in writing. Our buyer's tool hub helps you compare.
- Landlords: list your flat's carpet area honestly. Tenants and companies notice, and accurate listings let faster. You can list with us.
- Tenants: use carpet area to compare rents fairly.
Frequently asked questions
Does RERA carpet area include the balcony?
No. Exclusive balcony, verandah and open terrace areas are excluded from carpet area and disclosed separately.
Does carpet area include internal walls?
Yes. RERA carpet area includes the area under internal partition walls, but not external walls.
How many sq ft is one square metre?
About 10.764 sq ft.
Related reading
Comparing two flats and the numbers don't add up? Book a video call or WhatsApp me.
Warmly,
Yanik
General information, not legal advice.
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