The Three Area Definitions You Must Know
Before RERA standardised property pricing in 2016, India's real estate market was awash with area confusion. Developers quoted different numbers depending on what made their prices look attractive. Understanding the three area concepts is the foundation of any meaningful property comparison in India.
Carpet Area: The RERA Standard
Carpet area is the net usable floor area of an apartment — literally, the area on which you can lay a carpet. Under RERA's definition (Section 2(k) of RERA 2016):
- Includes: all rooms (bedroom, living, kitchen, toilets, study), internal partition walls, internal corridors
- Excludes: the thickness of outer walls, open terrace, common areas
- Balcony/verandah: treated as 50% of actual area and added to carpet area under RERA's calculation
RERA mandates that all residential project pricing must be disclosed on a carpet area basis. The RERA portal's Form-1 shows the carpet area per unit type for registered projects.
Built-up Area
Built-up area = carpet area + the thickness of outer walls + dry balcony (100%). Essentially, it's the area within the outer walls of your unit including the walls themselves. Built-up area is typically 10–20% more than carpet area.
Example: If your carpet area is 1,000 sqft, the built-up area is typically 1,100–1,200 sqft. The difference accounts for wall thickness on all four sides of the apartment.
Super Built-up Area (SBA): The Source of Confusion
Super built-up area = built-up area + your proportionate share of common areas (lobby, staircase, lift shaft, clubhouse, amenity areas, corridors on your floor). The proportionate share is calculated as your built-up area divided by the total built-up area of all units in the building, multiplied by the total common area.
SBA is typically 30–45% more than carpet area. In Mumbai's high-rise buildings where common areas are large, SBA can be 45–50% more than carpet area. In smaller buildings in Hyderabad or Bangalore, it may be 30–38% more.
How Pricing Tricks Worked Before RERA
Before 2016, a developer could quote ₹7,500/sqft on super built-up area. A buyer seeing this price compared it against another developer quoting ₹9,500/sqft on carpet area and concluded the first was cheaper. They were wrong — the effective carpet-area rate for the "cheaper" project was actually ₹7,500 × 1.40 = ₹10,500/sqft, making it more expensive.
This manipulation was rampant across India. Buyers routinely paid for phantom square footage — lobby, lift shafts, and corridors they shared with 200 other families but paid for as if it were their private space.
The RERA 2016 Fix
RERA Section 4(2)(d) requires all developer registrations to disclose the carpet area per apartment type. The sale agreement must state the price on a carpet area basis. Advertising on super built-up area is technically non-compliant with the spirit of RERA's disclosure requirements.
In practice, some developers still advertise super built-up area in marketing materials but disclose carpet area in the formal RERA registration and sale agreement. Always verify the RERA portal figure for the carpet area and calculate your effective rate on that basis.
How to Spot a Non-Compliant Builder
- Brochure prominently displays a large area number (e.g., "2,200 sqft") but the RERA portal shows 1,550 sqft carpet area — a 42% loading factor that is unusually high.
- Price per sqft in the brochure seems attractively low but the effective carpet area rate is at or above market.
- Builder refuses to clarify which area definition their price is based on.
- BBA states price in terms of "super built-up area" without separately disclosing carpet area price.
Loading Factors by City (Approximate)
| City | Typical SBA/Carpet Ratio | Notes |
|---|---|---|
| Mumbai (high-rise) | 1.40–1.50 | Large common areas in towers |
| Hyderabad | 1.35–1.42 | Premium projects higher |
| Bangalore | 1.30–1.38 | Varies significantly by builder |
| Chennai | 1.28–1.35 | Lower-rise stock keeps it lower |
| Delhi NCR | 1.35–1.45 | Group housing higher loading |
| Pune | 1.30–1.38 | Comparable to Bangalore |
Balcony and Terrace: Special Cases
- Balcony: Under RERA's carpet area definition, the balcony (open to sky, attached to unit) is counted at 50% of its actual area when computing the carpet area disclosed on the RERA portal. So a 100 sqft balcony adds 50 sqft to the disclosed carpet area.
- Terrace: An exclusive terrace attached to a top-floor or penthouse unit is typically NOT counted in carpet area. It is treated as an additional amenity and often sold at a separate rate or included as a perk.
How to Verify the Carpet Area Independently
- Visit the state RERA portal and search for the project by RERA number.
- Download Form-1 or the project registration certificate.
- Look for "Unit Type" details — it will show carpet area per flat type (1BHK, 2BHK, etc.).
- Compare this with what the developer's brochure states and what the BBA will be signed for.
For a quick carpet area to built-up conversion, use our carpet area calculator. To see how carpet area efficiency factors into our overall project ratings, visit our score methodology page.
FAQ
If I pay for super built-up area, do I own the common areas?
No. Paying for super built-up area gives you a share of the common areas as a co-owner through the housing society — you do not own those areas exclusively. The Supreme Court has held that builders cannot sell common areas separately or deny residents access to them.
Can the carpet area of my flat change after RERA registration?
RERA Section 14(2) allows a variation of up to 3% from the carpet area declared in the agreement without buyer consent. Any variation beyond 3% requires buyer consent and proportionate price adjustment.
Does GST apply on carpet area or super built-up area?
GST on under-construction properties is calculated on the total agreement value (which should be carpet-area based under RERA), not separately on the area metric. The rate (5% or 1%) applies to the total consideration stated in the BBA.