Carpet area is the actual usable floor space within your unit's walls; built-up area adds wall thickness and balconies; super built-up area further adds a share of common spaces like lobbies and stairwells — and under India's RERA framework, only carpet area is the legally standardised figure a promoter must quote.
The three terms, defined plainly
Carpet area is the net usable floor area inside your unit's internal walls — what you could genuinely lay carpet on. Built-up area (sometimes called plinth area) adds the thickness of your unit's own walls and any balcony or deck attached to it. Super built-up area, sometimes called saleable area, goes further and adds a proportional share of shared spaces such as lift lobbies, stairwells and common corridors.
Why the difference matters when comparing two projects
Two apartments advertised at the same super built-up area can have meaningfully different carpet areas depending on how much shared space (loading factor) each building allocates. A wider tower with more lobbies and amenity corridors will typically have a higher loading factor, meaning less of the marketed number is space you actually live in.
Always ask for the exact carpet area figure — ideally the one stated in the Agreement for Sale, which is the legally binding number — rather than comparing projects only by their marketed super built-up figures.
Where to find the authoritative number
Under RERA, promoters are required to quote carpet area in project disclosures and the Agreement for Sale. Cross-check the number shown to you verbally or in a brochure against what appears in the registered RERA project details and in the draft agreement before signing.