Buying
Carpet, built-up and super built-up area — and which one RERA made count
6 min read · Last verified
In short
Carpet area is the net usable floor area within the walls of a flat, defined by RERA and the basis on which homes must now be sold. Built-up area adds the walls, and super built-up area adds a share of common spaces. The difference between carpet and super built-up is the loading factor, and it varies enough between projects to make headline price-per-square-foot comparisons meaningless.
Key facts
- Carpet area
- Net usable floor area within the flat's walls
- Built-up area
- Carpet area plus the walls
- Super built-up area
- Built-up area plus a share of common areas
- Statutory basis
- Carpet area is defined in the RERA Act
- Sales basis
- Homes must be sold on carpet area
- Loading factor
- The gap between carpet and super built-up; varies by project
Before RERA, a developer could quote whichever measurement flattered the price, and two projects quoting the same rate per square foot could be offering materially different amounts of actual floor.
RERA fixed the definition and required sales to be made on carpet area. The other measures still circulate in marketing, so it remains worth knowing exactly what each one includes.
What each measure covers
The three measures are nested: each includes the one before it plus something more.
| Measure | Includes | Excludes |
|---|---|---|
| Carpet area | Net usable floor area within the flat, including internal partition walls | External walls, service shafts, exclusive balcony or verandah area, exclusive open terrace |
| Built-up area | Carpet area plus the walls of the flat | Common areas of the building |
| Super built-up area | Built-up area plus a proportionate share of common areas — lobbies, staircases, lifts, amenity spaces | Nothing, in practice — it is the widest measure |
The RERA definition of carpet area is the one that governs the sale. Marketing material may still quote the others alongside it.
Loading, and why it makes price comparison hard
Loading is the gap between carpet area and super built-up area, expressed as a percentage. A project with heavy amenity provision — large lobbies, wide corridors, extensive shared facilities — has more common area to distribute and therefore a higher loading.
That is not necessarily bad. Those common areas are real and you use them. But it means a rate quoted on super built-up area is not comparable between two projects with different loading, and the project with the lower headline rate can easily deliver less actual floor.
- Always compare on carpet area, never on super built-up.
- Ask for the loading percentage explicitly; it is rarely volunteered.
- Higher loading is not automatically worse — it may reflect amenities you want.
- It is worse when you are paying for it without knowing.
What RERA actually changed
The Act defines carpet area and requires that a flat be sold on that basis, with the carpet area stated in the agreement. That removed the ambiguity that made pre-RERA comparison unreliable.
It did not abolish the other measures or stop them appearing in marketing. A brochure can still show a super built-up figure. The number that governs is the carpet area in the agreement, and that is the number to hold on to.
Balconies, terraces and the detail that surprises people
The RERA definition excludes exclusive balcony, verandah and open terrace area from carpet area, while including the area under internal partition walls. Buyers frequently expect the opposite on both counts.
The practical effect is that a flat with a large balcony has that balcony sitting outside the carpet figure. It is still yours and still useful — it simply is not in the number. Ask how balcony area is stated separately so you know what you are getting.
How to use this when comparing projects
The discipline is short and it removes most of the confusion.
- Get the carpet area in writing for the specific unit, not the typical unit.
- Divide the all-in cost by carpet area to get a comparable rate.
- Ask separately for balcony and terrace area so you can weigh it.
- Ask for the loading percentage, and note how it differs across your shortlist.
- Confirm the carpet area stated in the agreement matches what you were shown.