Free tool
Carpet, built-up and super built-up area calculator.
Estimate carpet area from built-up or super built-up area (and back) using the wall and loading percentages of the project.
Usable share of super built-up: 67%. Builders must disclose carpet area under RERA — use their figure when you have it.
Estimates for information only. Confirm figures with your bank, builder, accountant or the local revenue office.
How it works
The maths, in plain words.
- 01
Carpet area
Under the RERA Act, carpet area is the net usable floor area of an apartment, excluding external walls, service shafts, exclusive balconies or verandahs and open terraces, but including internal partition walls.
- 02
Built-up area
Carpet area plus the walls (and, by many definitions, balconies). A wall factor of around 10–20% is common, but it varies.
- 03
Super built-up area
Built-up area plus a share of common areas — lobbies, lifts, stairs, amenities — the “loading”. Builders must state the carpet area under RERA; always ask for it.
Questions
Frequently asked.
Is the loading percentage fixed?
No. It depends on the project’s common areas and amenities. Use the builder’s figures when you have them; this calculator is for estimates.
Which area should a price per sq ft use?
Compare prices on carpet area wherever possible — it is the area you actually use and the one RERA requires builders to disclose.
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