Why the Numbers on a Brochure Are Never the Whole Story
When a builder quotes you a flat at ₹7,500 per sq ft, the first question you should ask is: per sq ft of what? In Indian real estate, three different area definitions are in active use — and mixing them up can cost you lakhs of rupees. This guide explains each term clearly, shows you how to convert between them with real numbers, and tells you why Brickplot only publishes carpet-area prices in its project reviews.
The Three Area Definitions You Must Know
1. Carpet Area
Carpet area is the actual usable floor space inside your apartment — the area where you can literally lay a carpet. Under Section 2(k) of the Real Estate (Regulation and Development) Act, 2016 (RERA), carpet area is defined as the net usable floor area of an apartment, excluding the area covered by external walls, areas under services shafts, exclusive balcony or verandah area, and exclusive open terrace area. Internal walls — the partition walls within the apartment — are included in the carpet area calculation under RERA.
This is the most honest and consistent measure of what you are actually buying. It is the only area definition that does not change based on what the builder decides to include or exclude.
2. Built-up Area
Built-up area adds the thickness of the outer (external) walls and the area of your exclusive balcony or terrace to the carpet area. As a rough rule, built-up area = carpet area multiplied by 1.10 to 1.15, meaning it is typically 10 to 15 percent larger than carpet area. Most builders no longer use built-up area as a pricing basis — it has been largely superseded by super built-up area in marketing materials.
3. Super Built-up Area (Saleable Area)
Super built-up area, also called saleable area, is built-up area plus a proportionate share of common areas — lobby, staircase, lift shaft, gym, club, security cabin, corridors, and sometimes even the landscaped garden and swimming pool. Builders freely choose what to include in this calculation. There is no single standard definition, which is precisely why it is misleading.
The ratio of super built-up area to carpet area is called the loading factor (or loss factor), and it can be as high as 40 to 55 percent in large luxury high-rise towers in Mumbai, Bengaluru, and Gurugram.
The Loading Factor: How to Calculate It
The loading factor tells you how much of the quoted area is actual living space versus shared areas you will never use exclusively. The formula is straightforward:
- Loading factor (%) = (Super Built-up Area minus Carpet Area) divided by Carpet Area, multiplied by 100
- Alternatively: Carpet Area = Super Built-up Area divided by (1 plus Loading Factor expressed as a decimal)
Worked example: A builder quotes a 1,500 sq ft super built-up flat at ₹8,000 per sq ft. The RERA carpet area disclosed is 975 sq ft.
- Loading factor = (1,500 minus 975) divided by 975 multiplied by 100 = 53.8%
- Effective carpet-area price = ₹8,000 multiplied by 1,500 divided by 975 = ₹12,308 per sq ft
- You are paying ₹12,308 per sq ft of actual liveable space, not ₹8,000
That is a 54 percent premium hidden behind a marketing number. Two projects in the same micro-market can have identical super built-up prices but wildly different carpet-area prices depending on how each builder defines common areas. Without normalising to carpet area, you cannot make a meaningful comparison.
What RERA Changed for Buyers
Before RERA, builders were legally free to quote any area definition they liked. Post-RERA (mandatory from May 2017 for new registrations), all registered projects must disclose the RERA carpet area of each unit in the allotment letter and in the sale agreement. More importantly, you pay only for carpet area — the pricing basis in the registered agreement must be carpet area, not super built-up area, for RERA-registered projects.
This does not mean super built-up area has disappeared from marketing brochures. Builders still use it freely in ads, hoardings, and website listings. RERA only mandates carpet area disclosure in the formal agreement — not in informal marketing. Buyers must therefore look past the brochure number and demand the RERA carpet area figure before negotiating or comparing projects.
State-Specific Nuances to Watch
- Maharashtra: MahaRERA mandates carpet area disclosure in every registered advertisement. Check rera.mahaonline.gov.in for the officially registered carpet area of any project.
- Karnataka: RERA Karnataka (rera.karnataka.gov.in) requires quarterly updates; the carpet area on the portal must match what is stated in your allotment letter. Discrepancies are reportable.
- Telangana and Andhra Pradesh: Older projects pre-dating RERA registration often still quote super built-up informally in materials. Always demand the RERA carpet area figure before negotiating the price.
- NCR (Haryana and UP): Loading factors in large high-rise projects here routinely exceed 45 percent. Some projects even exceed 55 percent loading. Always compare on carpet area and never on super built-up area in this market.
- Chennai: Chennai's housing stock includes many older buildings predating RERA. For resale purchases, calculate the loading factor yourself using the registration document area and the quoted saleable area.
Practical Conversion Reference
- Carpet to Super Built-up (typical mid-rise): multiply by 1.25 to 1.35
- Carpet to Super Built-up (large luxury high-rise): multiply by 1.40 to 1.55
- Super Built-up to Carpet (typical): multiply by 0.71 to 0.80
- Always demand the RERA carpet area in writing — never estimate from brochure super built-up numbers
- When comparing two projects, always convert both to carpet-area price per sq ft before comparing
Common Builder Tactics to Watch Out For
Some builders advertise an attractively low price per sq ft but use an unusually large super built-up area to reach the same total cost. Others use a moderate loading factor but include amenities in the common area calculation that add little day-to-day value — a rooftop deck used twice a year, or a jogging track you share with 800 families. The loading factor is a real cost to you regardless of whether you use those amenities.
Another common tactic is quoting carpet area in the headline but using a definition slightly different from RERA carpet area — for example, including the balcony. RERA explicitly excludes exclusive balcony area from carpet area. Always ask which definition the builder is using and cross-check against the RERA portal.
Brickplot's Take
Every project reviewed on Brickplot displays pricing per sq ft of RERA carpet area exclusively. We back-calculate from the builder's published super built-up price and the RERA-registered carpet area to give you an apples-to-apples comparison across projects in the same city. If a project has an unusually high loading factor (above 45 percent), we flag it prominently in the project scorecard under the Value for Money axis. Our editorial view: a loading factor above 40 percent in a mid-segment project is a red flag — it usually signals either over-engineered common areas that inflate the maintenance charge base, or a deliberate attempt to obscure the real per-sq-ft cost from buyers who do not check the fine print.