Calculate plinth area, carpet area, built-up area, and super built-up area for Indian construction. Includes FSI/FAR calculation and all standard area conversion ratios.
Carpet area is the usable floor space inside walls — the area you can actually place a carpet. Plinth area (also called built-up area per some definitions) includes the carpet area plus the thickness of external walls, typically 10% more than carpet area.
Super built-up area includes your flat's built-up area plus a proportionate share of common areas — lobby, staircase, lift, corridor, club house. Builders typically use a loading factor of 1.25 to 1.35x the carpet area.
Carpet area x 1.10 = Plinth area. Plinth area x 1.15 = Built-up area. So carpet x 1.265 gives approximate built-up area. This calculator converts in any direction.
FSI (Floor Space Index) or FAR (Floor Area Ratio) = Total built-up area / Plot area. An FSI of 2 means you can build 2 sq m of floor area for every 1 sq m of plot. FSI limits are set by local municipal authorities.
Under RERA, carpet area is the net usable floor area excluding the area covered by external walls, service shafts, balconies, and verandas. It is the most transparent area definition for homebuyers.
Plinth area rate is the construction cost per square foot of plinth area. It is used for quick building cost estimation. Multiply plinth area by local construction rate per sq ft to get approximate total cost.