Area & Measurement
What is Plinth Area?
The number the building department uses. It is not the number the sales office uses, and knowing the difference tells you something.
The short answer
Plinth area is the floor's footprint, measured to the OUTER face of the external walls — so the walls are included.
It is a regulatory and construction figure. It is used to compute FSI, to check ground coverage, and to cost the build.
It is not what you are sold. Builders sell super built-up. The gap between the two is where a great deal lives.
What plinth area is
Stand outside the building and measure the footprint of one floor — to the outside of the external walls. That is the plinth area of that floor.
It includes:
- The internal floor area
- The thickness of all walls — internal and external
- Internal shafts, ducts and pillars within the footprint
It generally excludes open balconies, open terraces, and voids — though the treatment varies by local bye-law, and that variation is not trivial.
Plinth vs built-up vs carpet
| Term | What it includes | Who uses it |
|---|---|---|
| Carpet area | The usable floor within the walls. Wall thickness EXCLUDED. | RERA. The law. You. |
| Plinth area | Carpet + all wall thickness, measured to the outer face | Building bye-laws. FSI. Construction costing. |
| Built-up area | Broadly the same idea as plinth, sometimes with balconies counted | Builders, loosely. Not a fixed legal term. |
| Super built-up area | Built-up + your share of every common area — lobby, lift, clubhouse, corridors | The sales office. Not defined in law at all. |
Only CARPET AREA is defined in law — Section 2(k) of RERA. Plinth area is defined in building bye-laws. Built-up and super built-up are commercial conventions, and 'super built-up' in particular is whatever the builder decides it is.
Where plinth area is actually used
- FSI calculations. The permitted floor area is measured this way.
- Ground coverage. The footprint on the plot.
- Construction costing. A builder costs per square foot of plinth — because that is what they actually build.
- Building plan approval. The authority checks plinth against the bye-laws.
- Property tax, in some cities.
Why you should care
Plinth area is a real, physical, regulated number. It is on the sanctioned plan.
Super built-up area is not. It is carpet + walls + a share of the common areas that the builder chose to allocate to you.
So: if the super built-up figure is far above the plinth area, ask what the difference consists of.
You are entitled to an answer, and the answer should be specific: “the lobby, the two lifts, the staircases, the corridors, the clubhouse, the gym.” If it is vague, that is informative.
Your undivided share of the land.
Carpet, plinth, built-up, super built-up — every one of them measures the BUILDING.
And the building depreciates. The land appreciates.
So the single most important number in your purchase — the one that determines what your flat is worth in twenty years — appears in none of these figures at all.
Ask for the UDS.
Frequently asked questions
What is plinth area?
The built-up footprint of a floor, measured to the outer face of the external walls — so all wall thickness is included. It is a regulatory and construction figure, used for FSI calculations, ground coverage, building plan approval and construction costing.
What is the difference between plinth area and carpet area?
Carpet area is the usable floor within the walls, excluding wall thickness — and it is the only definition fixed in law, under Section 2(k) of RERA. Plinth area includes all the wall thickness, measured to the outer face. Plinth is what the building department uses; carpet is what you actually walk on.
Is plinth area the same as built-up area?
Broadly similar in idea, but 'built-up area' is not a fixed legal term — it is a commercial convention, and different builders include different things (balconies, for instance). Plinth area is defined in building bye-laws. Super built-up is defined nowhere at all.
Why does plinth area matter to a buyer?
Because it is a real, regulated number on the sanctioned plan — and super built-up is not. If the super built-up figure is far above the plinth area, you are entitled to ask what the difference consists of, and the answer should be specific. If it is vague, that is informative.