Two flats can both be advertised at 1,400 square feet and differ by 150 square feet of usable floor. The difference is the area definition. Our existing article on the three terms covers the basics; this one focuses on the legal definition, the Bengaluru loading numbers that have been reported and a worked example that you can reproduce on your own price sheet.

The RERA definition, in the Act's words

Section 2(k) of the Real Estate (Regulation and Development) Act, 2016 defines carpet area as the net usable floor area of an apartment, excluding the area covered by external walls, areas under service shafts, exclusive balcony or verandah area and exclusive open terrace area, but including the area covered by internal partition walls of the apartment (as quoted by TaxGuru).

The Act's explanations describe an exclusive balcony or verandah and an exclusive open terrace as areas appurtenant to the net usable floor area meant for the exclusive use of the allottee. In plain terms: the rooms you can walk and furnish count; the thickness of the outer wall, the shaft and your balcony do not.

The other two terms

  • Built-up area: carpet area plus wall thickness, balcony and utility spaces (PropNewz, 23 September 2026).
  • Super built-up area: carpet area plus a proportionate share of common areas such as lobbies, staircases and corridors. This is the figure builders typically advertise (PropNewz).
  • Neither is a legal basis for sale in a registered project. Under RERA, sales in registered projects are based on carpet area; the rule applies to projects above 500 square metres of land or more than 8 apartments (Landeed, PropNewz).

Loading in Bengaluru: what has been reported

  • OneCityProperty (10 September 2026) quotes ranges of 25 to 30 percent loading for budget and mid-segment apartments, 30 to 38 percent for premium and 35 to 45 percent for luxury projects. These are the publisher's ranges, not an official standard.
  • PropNewz (23 September 2026) reports research cited in 2025 that puts Bengaluru's average loading at 41 percent, so buyers receive roughly 60 percent of the paid-for area as carpet, up from about 30 percent in 2019. The carpet share ranges from about 56 percent for compact one-bedrooms to 72 percent for large premium homes in the same report.
  • Publishers may define loading as the non-carpet share of super built-up area or as the extra area relative to carpet area, so read the definition before comparing two sources. In our example we use the share of super built-up area.

A worked example (illustrative numbers)

Take a hypothetical 3 BHK advertised at 1,400 sq ft super built-up and priced at ₹10,000 per sq ft of SBA. These are our own round numbers to show the arithmetic, not a real project.

  • Price: 1,400 sq ft x ₹10,000 = ₹1.4 crore.
  • RERA carpet area on the agreement: 1,000 sq ft.
  • Built-up area (carpet plus walls plus balcony): 1,150 sq ft.
  • Implied common-area and other loading: 1,400 minus 1,000 = 400 sq ft, or about 29 percent of the SBA.
  • True rate per sq ft of carpet area: ₹1.4 crore divided by 1,000 = ₹14,000, which is 40 percent more than the ₹10,000 advertised on SBA.
  • Now compare with a second hypothetical flat: 1,380 sq ft SBA at ₹10,200 per sq ft = ₹1.41 crore, but with 1,100 sq ft of carpet area. Its carpet-area rate is about ₹12,800. The apparently pricier flat is cheaper per usable foot.

What RERA allows on area changes

RERA's rules on carpet area variation, as summarised by PropNewz, let a promoter charge for an increase in carpet area of up to 3 percent at the agreed rate, while a reduction in carpet area must be compensated, with a full refund where the shortfall is not accepted. That protection exists in the Act, but you can only use it if your agreement states the carpet area clearly.

How to compare two projects fairly

  • Ask for the carpet area in the draft agreement and the sanctioned plan, not the brochure.
  • Divide the all-in price (base, floor rise, preferred location, parking, club and corpus charges) by the carpet area.
  • Check whether balconies are counted in built-up and in the price. Under RERA they are excluded from carpet area, so a flat with large balconies will show a lower carpet share.
  • Compare the layout: a smaller carpet area with good proportions can live larger than a larger one with wasted corridors.
  • Remember what RERA covers: a project below the threshold may not be registered, so verify on the K-RERA portal.

Our view

The most useful number in a flat purchase is the all-in price per square foot of carpet area. It converts any brochure to one yardstick. If a seller cannot state the carpet area in writing, treat that as a reason to look elsewhere.