Super built-up versus carpet area: what you actually bought
The gap can be a third of your purchase price. It is also entirely knowable in advance.
Three area figures are used in Indian property and they describe different things. Understanding which one you are being priced on is the difference between comparing properties accurately and comparing them meaninglessly.
The three numbers
Carpet area is the usable floor area within the walls of your unit, the space you can actually put furniture on. Built-up area adds the thickness of the walls and typically the balcony. Super built-up area adds your proportionate share of common spaces: lobbies, staircases, lifts, corridors, sometimes amenities.
The gap between carpet and super built-up, the loading, commonly runs between twenty-five and forty per cent.
Why it matters beyond the headline
Two properties quoted at the same rate per square foot can differ substantially in what you receive, purely because of different loading factors. Comparing rates without normalising to carpet area is comparing nothing at all.
The Real Estate (Regulation and Development) Act defines carpet area specifically and requires it to be disclosed for registered projects. That was a meaningful reform. It did not stop pricing conversations from happening in super built-up terms, because the resulting rate sounds lower.
What to ask for
The carpet area figure in writing, and the loading percentage. Then compute the price per square foot of carpet area and use only that number when comparing options. A property that looks expensive on carpet-area maths and cheap on super built-up maths is not cheap. It simply has a higher loading.
Resale implications
Your eventual buyer will run the same calculation, or their advisor will. A high loading factor does not disappear because you accepted it, it follows the unit, and it prices into your exit exactly as it priced into your entry.