Area & Measurement
What is Usable Area?
There is exactly one area definition in Indian law. Everything else — usable, saleable, chargeable, efficiency — is a word somebody invented to sell you something.
The short answer
"Usable area" is not defined in law. Nor is "saleable area", "chargeable area", "efficiency ratio", or "carpet area (builder's definition)".
Only CARPET AREA, under RERA Section 2(k), has a legal definition.
Which means: when a builder quotes you anything else, they are quoting a number they made up — and the only correct response is to ask for the RERA carpet area.
The one legal definition
The net usable floor area of an apartment, excluding the area covered by the external walls, areas under services shafts, exclusive balcony or verandah area and exclusive open terrace area — but including the area covered by the internal partition walls of the apartment.
That is it. That is the only area definition fixed in Indian law.
The promoter must disclose it. It goes in the agreement. It is legally binding. If they deliver less, you get a refund with interest.
The invented ones
| Term | What it usually means | Defined in law? |
|---|---|---|
| Carpet area | Net usable floor, per RERA Section 2(k) | YES — the only one |
| Usable area | Whatever the builder says | NO |
| Saleable area | Usually = super built-up | NO |
| Chargeable area | The area they charge you for | NO |
| Super built-up area | Carpet + walls + your share of common areas | NO |
| Built-up area | Roughly carpet + walls. Varies. | NO |
| Efficiency ratio | Carpet ÷ super built-up | NO |
| Plinth area | Footprint to the outer walls | In building bye-laws (not RERA) |
Seven of these eight are commercial conventions. Any builder can define them however they like — and different builders do. Which means a number quoted in any of them is not comparable with the same number from another project.
The oldest trick in Indian real estate
If every builder quoted price per square foot of RERA carpet area, you could line up five projects on a sheet of paper and instantly see which was cheapest.
That is precisely why almost none of them do.
Instead you get ₹9,000 per sq ft of super built-up — a number that depends entirely on a loading factor the builder chose, which is not capped, not disclosed unless you ask, and different at every project.
You cannot compare it. That is the feature, not the bug.
What to do — and it is one sentence
Ask it every time. Of every builder. For every unit.
They must give it to you. It is a statutory disclosure, it is in the RERA filing, and it goes into your agreement.
Then do the only calculation that matters:
Total all-in price ÷ RERA carpet area
That number is comparable between projects, between cities, between builders. Nothing else is.
Do it for five projects and you will discover that the one with the lowest advertised rate is frequently not the cheapest at all — and that the gap can be lakhs.
And when someone quotes you a "usable area", or a "saleable area", or an "efficiency ratio", the right response is friendly and entirely deflating:
"That's helpful — and what's the RERA carpet area?"
Frequently asked questions
Is usable area a legal term?
No. Neither is saleable area, chargeable area, super built-up area, built-up area or efficiency ratio. Only CARPET AREA has a legal definition — Section 2(k) of the RERA Act. Everything else is a commercial convention that each builder defines for themselves.
What is the difference between usable area and carpet area?
Carpet area is defined in law and legally binding: the net usable floor area excluding external walls, service shafts, balcony and open terrace, but INCLUDING internal partition walls. 'Usable area' is whatever the builder says it is. If they deliver less carpet area than the agreement states, you get a refund with interest. There is no such remedy for 'usable area'.
Why do builders quote super built-up area?
Because it cannot be compared. If every builder quoted price per square foot of RERA carpet area, you could line up five projects and instantly see which was cheapest. Super built-up depends on a loading factor the builder chose, which is not capped and differs at every project — so the numbers are not comparable. That is the feature, not the bug.
What is the only number I should compare between projects?
Total all-in price divided by RERA carpet area. That is comparable between projects, cities and builders. Nothing else is. Do it for five projects and you will often find the one with the lowest advertised rate is not the cheapest at all — and that the gap runs to lakhs.
Can a builder refuse to tell me the carpet area?
No. It is a statutory disclosure under RERA, it appears in the project's RERA filing, and it must be stated in your agreement for sale. If a builder is reluctant to give it to you in writing, that reluctance is itself the most useful information you will get all day.