Also known as Floor space index, FAR (floor area ratio)
Planning authorities set FSI (called FAR, floor area ratio, in Delhi and many northern cities) through development control regulations. It varies by city, zone, road width and use, and can be raised by paying premiums, using TDR or under schemes for redevelopment or affordable housing.
FSI drives land value: the same plot is worth more where more can be built. In redevelopment, the extra FSI available beyond what the existing building uses is what pays for residents’ larger flats and the developer’s sale component.
What counts towards FSI is defined in each city’s rules. Some areas, such as certain balconies, staircases or lift wells, may be excluded or charged separately, so two buildings with the same FSI can look different.
Example
A society in Pune sits on a 2,000 sq m plot and its old building uses 2,400 sq m of floor area. If the rules for that plot allow a total of 4,000 sq m with premium FSI and TDR, a developer can build 1,600 sq m more. That margin pays for construction, larger flats for members and the developer’s sale units.
Figures are illustrative, not market rates.
Questions about FSI
Are FSI and FAR the same?
Yes, they describe the same ratio. Maharashtra and some other states say FSI; Delhi and many northern states say FAR. Some codes express FAR as a number like 150 instead of 1.5.
Who decides the FSI of a plot?
The city’s development control or building bye-laws, made by the state or local planning authority. The permissible FSI depends on the zone, road width, plot size and use, and may be increased with premiums or TDR where rules allow.
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