Why is carpet area so much smaller?

Because super built-up includes your share of lobbies, staircases, lifts and amenities. A thirty percent loading factor means a 1,200 sq ft flat has around 850 sq ft of usable floor.

Which area should I compare between projects?

Carpet, always. It is the only one defined the same way everywhere and the only one RERA requires to be disclosed.

Construction & HomelandIndia only

Carpet vs Built-Up vs Super Built-Up Area

Carpet, built-up and super built-up area converted between each other, with the effective rate on usable space. RERA requires carpet area to be disclosed, and the effective rate on it is usually a third above the quoted headline.

Also called: carpet area calculator, super builtup to carpet.

Carpet area

854.7

854.7 sq ft of carpet area from 1,200 sq ft of super built-up area. At 8,500 per sq ft quoted on the super built-up area, the effective rate on usable space is ₹11,934, which is 40.4% higher.

Built-up area

923.08

Super built-up area

1,200

Total price

₹1,02,00,000

Effective rate on carpet area

₹11,934

Premium over the quoted rate

40.4%

Quoted on

super built-up area

How this is calculated

Method and background

How this is calculated

Carpet area is the floor you can actually walk on. Built-up adds wall thickness and balconies. Super built-up adds a share of lobbies, staircases, lifts and amenities, and the loading factor covering that is typically twenty-five to forty percent. Since a rate quoted per square foot of super built-up is spread over space you cannot use, the effective rate on carpet area is the honest comparison and is materially higher. RERA requires carpet area to be stated in the agreement for exactly this reason.

the loading factor covers shared areas and the wall allowance covers thickness

l: Loading factor
w: Wall allowance

Worked examples

Each of these is asserted on every build. If a change to the engine ever moved one of these answers, the build would fail before the page could print it.

a 1,200 sq ft super built-up flat

Area: 1,200
That area is: Super built-up
Loading factor: 30%
Wall thickness allowance: 8%
Rate per square foot: ₹8,500

Carpet area854.7

1200 / 1.3 / 1.08

Open this example

no loading makes built-up and super built-up equal

Area: 1,200
That area is: Super built-up
Loading factor: 0%
Wall thickness allowance: 0%
Rate per square foot: ₹8,500

Carpet area1,200

boundary

Open this example

Method and limits

What it assumes

A single loading factor, which varies by project and is often not disclosed clearly.

What it deliberately does not model

Builders define built-up area inconsistently, particularly on balconies and terraces.
The wall allowance is a convention rather than a measured figure.

Formula version 1.0.0 · definition 1.0.0 · India · Report a problem with this calculator

Frequently asked questions

Why is carpet area so much smaller?: Because super built-up includes your share of lobbies, staircases, lifts and amenities. A thirty percent loading factor means a 1,200 sq ft flat has around 850 sq ft of usable floor.
Which area should I compare between projects?: Carpet, always. It is the only one defined the same way everywhere and the only one RERA requires to be disclosed.