Carpet Area vs Built-Up vs Super Built-Up Area (Explained)

Carpet area is the usable floor you can actually put a carpet on; built-up area adds the walls and balcony; super built-up area adds your share of common spaces like the lobby and stairs. The gap between them is why a "1,200 sq ft flat" can have only ~850 sq ft you can use.

The three areas

Carpet area — the net usable floor area inside the flat, within the walls (excluding the thickness of external walls). This is the floor you live on. Under RERA, it excludes the external walls but includes internal partition walls.
Built-up area — carpet area plus the area of the walls and the balcony/terrace. Typically about 10–15% more than carpet area.
Super built-up area — built-up area plus a proportionate share of common areas (lobby, staircase, lift, corridors, sometimes amenities). This is the "saleable area" builders quoted for years, and it can be 25–40% more than carpet area.

The loading factor

Builders express the gap as a loading factor:

Super built-up area = Carpet area × (1 + loading factor)

A 30% loading factor means a 1,000 sq ft carpet flat is sold as 1,300 sq ft super built-up. Two projects quoting the same super built-up price can give very different usable space if their loading factors differ — so compare on carpet area, not super built-up.

Why RERA changed this

Before the Real Estate (Regulation and Development) Act, builders sold on super built-up area, and the loading factor was often vague. RERA now requires builders to declare and sell on carpet area with a standard definition, so buyers can compare like with like and know exactly what usable space they are paying for.

Quick comparison

Area type	Includes	Typical vs carpet
Carpet	Usable floor within walls	Base (100%)
Built-up	Carpet + walls + balcony	~110–115%
Super built-up	Built-up + share of common areas	~125–140%

Use our square feet to gaj and other land converters when comparing areas across listings that mix units.

Frequently asked questions

What is the difference between carpet area and built-up area? Carpet area is the usable floor inside the flat; built-up area is carpet area plus the walls and balcony, typically 10–15% more.

What is super built-up area? Built-up area plus a proportionate share of common areas like the lobby, staircase and lift — the "saleable area", often 25–40% more than carpet area.

Does RERA use carpet area? Yes. RERA requires builders to declare and sell on carpet area with a standard definition, so buyers can compare projects fairly.

How do I convert super built-up to carpet area? Divide the super built-up area by (1 + loading factor). At a 30% loading factor, 1,300 sq ft super built-up is 1,000 sq ft carpet.