Why interiors are priced on it
Because it is what the work relates to. Flooring covers carpet area. Joinery stands on it. Lighting lights it. Quote a rate of ₹1,900 per sq ft against a 1,000 sq ft carpet area and the project is ₹19 lakh; quote the same work against a 1,450 sq ft super built-up figure and the rate appears to be ₹1,310 — the same money, presented as 31% cheaper. This is the most effective legal way to make an interior quotation look competitive, and it is used constantly.
A worked comparison
| Basis | Area | Rate needed for ₹19,00,000 |
|---|---|---|
| Carpet area | 1,000 sq ft | ₹1,900 / sq ft |
| Built-up area | 1,150 sq ft | ₹1,652 / sq ft |
| Super built-up area | 1,450 sq ft | ₹1,310 / sq ft |
Before comparing any two per-sq-ft quotations, confirm which area each one uses. If they differ, the comparison is meaningless until you convert.
Measuring it yourself takes half an hour: internal length and width of each room at about a metre above the floor, multiplied and summed, with wardrobes and fixed joinery included because they stand on the floor. Do it before the first site visit and you will spot a mis-stated area immediately.
How to establish yours
- The sale agreement states it — since 2017, RERA requires the RERA carpet area in the agreement for registered projects.
- Measure it: internal length × width of each room, summed, excluding wall thicknesses.
- Property tax records and society records sometimes carry a figure; treat them as indicative.
- The difference between your measurement and the agreement figure is usually internal partition walls — RERA includes them, the plain-language definition does not.
Carpet area is also what our own rates use throughout this site. Compare built-up area and super built-up area, convert between them with the area converter, or read carpet versus built-up area. For costs, see interior design cost in Mumbai.
Frequently asked questions
Is carpet area the same as usable area?+
Broadly, yes, in everyday use. The technical difference is internal partition walls, which the RERA definition includes within carpet area and a plain reading of "usable" would not. For interior costing, the distinction is immaterial.
What percentage of super built-up is carpet area?+
Typically 60–75% in Mumbai, depending on the loading factor the developer applied. Older buildings with fewer amenities sit near the top of that range; new towers with clubhouses and large lobbies sit at the bottom.
Should interior costs be quoted on carpet area?+
Yes. It is what the work physically relates to. A rate quoted against built-up or super built-up area looks lower for identical work, which is precisely why it is sometimes presented that way.
Does carpet area include the balcony?+
No. Balconies, terraces, verandahs and shafts are excluded, and are usually stated separately in a sale agreement. For interior costing, we price balcony work as its own line rather than folding it into a per-sq-ft rate.