Quick answer: In carpet area vs built-up area, carpet area is the floor inside your walls. RERA carpet area adds the internal walls and is the only measure defined in law (RERA Act, 2016, Section 2(k)). Built-up area adds all the walls and usually the balcony. Super built-up area adds a share of the lobby, lifts and amenities. In the Mumbai region, 43% of the area buyers pay for is not their carpet area (ANAROCK, 2025).
Key facts
- The legal measure: RERA carpet area is the floor area of the home, including internal walls. External walls, service shafts, balconies and open terraces are left out (RERA Act, Section 2(k)).
- What builders must disclose: the carpet area of every home, with balcony and terrace areas listed separately (RERA Act, Section 4(2)(h)).
- Mumbai's loading: 43% in the Mumbai Metropolitan Region in early 2025, up from 33% in 2019 (ANAROCK).
- The price that matters: price per square foot of RERA carpet area. Relmo shows it for every project where a price is available.
Last verified: 29 October 2026. Compiled by Relmo from the RERA Act, 2016 and ANAROCK research.
When you compare homes, the carpet area vs built-up area question decides what a price really buys. The same flat can be quoted as 700, 740, 850 or 1,000 square feet. This guide shows each number on one floor plan, explains which one the law uses, and shows how to compare two homes fairly.
What is carpet area?
Carpet area is the floor you could cover with a carpet. It includes your bedrooms, hall, kitchen and bathrooms. It leaves out the walls and the balcony.
In the example flat in this guide, the carpet area is 700 square feet. That is two 132 sq ft bedrooms, a 300 sq ft hall, a 91 sq ft kitchen and a 45 sq ft bathroom. Every other measure starts from this number and adds something to it.
What is RERA carpet area?
RERA carpet area is carpet area plus the space under the internal walls. The Real Estate (Regulation and Development) Act, 2016, defines it in Section 2(k):
"carpet area" means 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 includes the area covered by the internal partition walls of the apartment.
So the internal walls between your rooms count. The outer walls, the balcony and any private terrace do not. In the example flat, the internal walls add 40 square feet, so the RERA carpet area is 740 square feet.
What is the difference between carpet area and RERA carpet area?
The internal walls. Plain carpet area measures only the floor you can walk on. RERA carpet area also counts the floor under the walls between your rooms. In most flats, the difference is small, often a few per cent.
What is built-up area?
Built-up area is carpet area plus the thickness of all the walls, inside and out, and usually the balcony. The RERA Act does not define it, so builders calculate it in different ways.
In the example flat, the external walls add 50 square feet and the balcony adds 60. That takes the built-up area to 850 square feet.
What is super built-up area?
Super built-up area is built-up area plus your share of the building's common areas. Those include the lobby, lifts, staircases, clubhouse and pool. It is also called saleable area. The RERA Act does not define it either.
In the example flat, your share of the common areas adds 150 square feet. That takes the super built-up area to 1,000 square feet, 300 more than the floor you can actually use.
How do the four measures compare?
Here is the same example flat, measured four ways.
| Measure | What it includes | Example flat | Defined in law? |
|---|---|---|---|
| Carpet area | The floor of every room | 700 sq ft | No |
| RERA carpet area | Carpet area + internal walls | 740 sq ft | Yes, Section 2(k) |
| Built-up area | RERA carpet area + external walls + balcony | 850 sq ft | No |
| Super built-up area | Built-up area + share of common areas | 1,000 sq ft | No |
The example flat is an illustration. The size of each step differs from building to building.
What is loading, and how much is it in Mumbai?
Loading is the share of the area you pay for that is not your carpet area. It covers walls, balconies and common areas.
ANAROCK, a property consultancy, tracks it across India's top seven cities. In the Mumbai Metropolitan Region, loading rose from 33% in 2019 to 39% in 2022, then 43% in the first quarter of 2025. That is the highest of the seven cities (NBM&CW, June 2025).
Across the top cities, ANAROCK says only about 60% of the space buyers pay for is liveable carpet area (Outlook Money). No rule caps loading today.
Why should you compare homes on RERA carpet area?
RERA carpet area is the only number defined in law, and the builder must declare it. The other three can hide very different homes behind the same figure.
Take two homes. Each costs ₹1 crore and each is sold as 1,000 sq ft of super built-up area. One has 800 sq ft of RERA carpet area. The other has 400 sq ft.
| Home A | Home B | |
|---|---|---|
| Price | ₹1 crore | ₹1 crore |
| Super built-up area | 1,000 sq ft | 1,000 sq ft |
| RERA carpet area | 800 sq ft | 400 sq ft |
| Price per sq ft of carpet area | ₹12,500 | ₹25,000 |
On paper the two look the same. In fact, Home B costs twice as much for every square foot you can use.
Is the balcony included in carpet area?
No. Under Section 2(k) of the RERA Act, an exclusive balcony, verandah or open terrace is left out of carpet area. Section 4(2)(h) asks the builder to list balcony and terrace areas separately. That is why balconies are often quoted on their own.
What must builders tell you under RERA?
When a project is registered, the builder must disclose the number, type and carpet area of the homes for sale. Balcony and open terrace areas are listed alongside, separately (RERA Act, Section 4(2)(h)).
Some state regulators go further. In January 2024, Uttar Pradesh's regulator told builders to sell homes on carpet area only (The Week).
How do you check a project's RERA carpet area in Mumbai?
Search the project on the MahaRERA website by its name or registration number. The project's details list each type of home with its carpet area.
Each project on Relmo shows its RERA carpet area for every configuration. The price per square foot is worked out on that carpet area too.
What does a square foot of carpet area cost in Mumbai?
It depends heavily on the area. Browse new homes in Mumbai on Relmo to see the price per square foot of RERA carpet area for every project where a price is available.
Key terms
- Carpet area: the floor of every room in a home, not counting walls or the balcony.
- RERA carpet area: carpet area plus the area under the internal walls, as defined in Section 2(k) of the RERA Act, 2016.
- Built-up area: carpet area plus all walls and usually the balcony. It is not defined in the RERA Act.
- Super built-up area: built-up area plus a share of common areas such as the lobby, lifts and amenities. It is also called saleable area.
- Loading: the share of the area you pay for that is not carpet area.
- Exclusive balcony or verandah area: a balcony or verandah attached to one home, for its owner's use only. It is left out of carpet area.
- MahaRERA: Maharashtra's real estate regulator, where projects in Mumbai are registered.
Where these numbers are uncertain
Two limits apply to the figures above.
- The example flat is an illustration. The step from one measure to the next differs from building to building.
- Built-up and super built-up area have no legal definition. Two builders can measure the same flat differently.
Find homes by RERA carpet area on Relmo
Every project on Relmo lists its RERA carpet area and, where a price is available, its price per square foot of carpet area, so homes are easy to compare like for like. Explore new homes in Bandra West, Chembur, Versova, Mira Road East and across Mumbai.
Using this guide? You're welcome to use the tables and diagrams on this page. Please credit and link to this page: "Source: Relmo, Carpet Area vs Built-up Area vs Super Built-up Area."
Sources: The Real Estate (Regulation and Development) Act, 2016 (PRS India) · Wikipedia: Real Estate (Regulation and Development) Act, 2016 · ANAROCK via NBM&CW, 9 June 2025 · ANAROCK via Outlook Money · The Week, 3 January 2024 · MahaRERA.
Frequently asked questions
What is the difference between carpet area, built-up area and super built-up area?
Carpet area is the floor inside your walls. Built-up area adds the thickness of the walls and usually the balcony. Super built-up area adds a share of common areas like the lobby, lifts and pool. Of the four measures, only RERA carpet area is defined in law.
What is RERA carpet area?
RERA carpet area is the net usable floor area of a home, including the area under internal walls. External walls, service shafts, exclusive balconies and open terraces are left out. The definition is in Section 2(k) of the RERA Act, 2016.
Is RERA carpet area the same as carpet area?
No. RERA carpet area adds the floor under the internal walls between rooms. Plain carpet area counts only the floor you can walk on. RERA carpet area is the measure builders must declare.
Is the balcony included in RERA carpet area?
No. Section 2(k) of the RERA Act leaves out exclusive balconies, verandahs and open terraces. Builders must list balcony and terrace areas separately, under Section 4(2)(h).
Which area should I compare when buying a flat?
Compare RERA carpet area, and the price per square foot of RERA carpet area. RERA carpet area is defined in law and declared by the builder. Two homes with the same super built-up area can have very different carpet areas.
What is a good loading percentage?
Lower loading means more of what you pay for is your own floor. ANAROCK found loading averaged about 40% across India's top cities in 2025. In the Mumbai region, the figure was 43%.
Is super built-up area legal?
Super built-up area is not defined in the RERA Act, 2016. The Act asks builders to declare carpet area, with balconies and terraces listed separately. Uttar Pradesh's regulator directed builders in January 2024 to sell on carpet area only.
Where can I find a project's RERA carpet area in Mumbai?
Search the project on the MahaRERA website by name or registration number. The project's details list each type of home with its carpet area. Relmo also shows the RERA carpet area for every configuration on each project page.
Why do builders quote super built-up area?
Super built-up area gives a bigger number, so the price per square foot looks lower. A home priced at ₹10,000 per sq ft of super built-up area costs more per sq ft of carpet area. With 43% loading, that becomes about ₹17,500.
What is built-up area in a flat?
Built-up area is carpet area plus the thickness of the internal and external walls, usually with the balcony added. The RERA Act does not define built-up area, so builders calculate it in different ways.
How much is loading in Mumbai?
Loading in the Mumbai Metropolitan Region was 43% in the first quarter of 2025, according to ANAROCK. Loading was 33% in 2019 and 39% in 2022, the highest of India's top seven cities.