Carpet, Built-Up and Super Built-Up: The Number That Decides What You Are Buying

Two flats, both advertised as 1,250 square feet, at the same price. One has 980 square feet of usable floor; the other has 870. That is the difference between a comfortable three-bedroom and a cramped one, and nothing in the listing tells you which is which.

The three numbers

Carpet area. The usable floor inside the walls — where you can actually lay carpet. Excludes external walls, balcony (treated separately under RERA's definition), and everything common.

Built-up area. Carpet plus the walls plus the balcony. Typically 10–20% above carpet.

Super built-up area. Built-up plus your allocated share of the common areas — lobbies, staircases, lifts, corridors, the clubhouse, sometimes the gym and the pool. This is the number in most advertisements.

Loading

Loading is the percentage the developer adds. Historically 25–30% was normal; some projects push past 40%, and heavily amenitised towers push further still.

The arithmetic:

Carpet 1,000 sq ft, loading 30% → super built-up 1,300 sq ft.

If the rate is ₹6,000 per sq ft on super built-up, the price is ₹78 lakh. On carpet, that is ₹7,800 per sq ft of actual floor.

The rate comparison two buyers make between two projects is meaningless unless both are on the same basis.

What RERA requires

For projects registered under RERA, carpet area must be disclosed and the sale agreement must state it. RERA also defines carpet area precisely — the net usable floor area, excluding the external walls, service shafts, exclusive balcony and open terrace, and including internal partition walls.

This is one of the most useful things RERA did for buyers, and it applies to registered projects; resale transactions in older buildings often still trade on loose numbers.

The questions to ask

1. What is the carpet area, in writing?
2. What is the loading percentage?
3. Is the balcony counted, and how?
4. Is the rate quoted on carpet or super built-up?

A developer or agent who will not answer the first question in writing is telling you something.

How to compare properly

Convert everything to price per square foot of carpet:

Total price ÷ carpet area

Do this for every shortlisted property. Rankings frequently reverse. The flat that looked expensive on advertised rate is often the one with honest loading.

For agents

Quoting carpet area unprompted is a differentiator. Buyers who have been through three site visits with three agents notice immediately when one of them leads with the real number, and it changes how they weigh everything else you say.