What is FSI?

• FSI stands for Floor Space Index also known as Floor Area Ratio (FAR).
• FSI means the ratio between the area of a covered floor (Built up Area) to
the area of that plot (land) on which a building stands.
• This numeric value indicates the total amount of area (on all floors) you
can build upon a plot.
How to Calculate FSI for Building?

FSI is regulated by Development control regulation department of a

particular location and according to the National Building Code of India.
They will regulate the FSI value based on city zone, type of building and
other amenities. Construction can only build up to the FSI imposed by the
government.

Assume you have a land of 2000 sq. ft. and you want to construct a building
on that land.
There are different types of buildings such as:
• Ordinary Building – Up to 2 floors less than 4 flats/dwelling units,
• Special Building – more than 2 floors not exceeding 4 floors,
• Multi-storeyed Building – Exceeding 4 floors
• Industrial Building, Group housing etc.
FSI can be found on state governments official website, it varies upon building
type and different zones.
Let say, your zone FSI is 1.5 for special buildings.
Now you can build (2000*1.5 ) 3000 sq. ft. covered area on your land.
It can be -

2 floors of 1500 sq.ft 3 floors of 1000 sq.ft

NOTE: If you want to build more floors and maintain the same FSI the size
of each floor reduces.
Area free of FSI DCR 35(2)

• Features permissible in R.G i.e. Clubhouse, sub-station, underground

tanks, pump room.
• Fitness Centre.
• Basement exclusively for parking and other ancillary uses like AC Plant
Room, AHU Rooms, Meter Rooms, DG Set rooms, STP, Underground
Tank in Basement.
• Society Office up to 12sq.m / 20 sq. m. or more than 20 flats.
• Lofts.
• Porches.
• Canopy.
• Chajja up to 1.2m from building line at lintel level only and 0.75m from
balcony at minimum 0.30m level difference with reference to the floor level
and thickness of chajja to be restricted to 0.15m.
• Parking spaces upto extent of 25% additional required for residential and
10% for commercial.
• Fire escape chutes of 1.5 x 2.5m.
• Refuge areas upto 4% of habitable flats of the floors above the refuge
floors served by it.
• Fire check floor / service floor of height not exceeding 1.8 m.
• Entrance lobbies in stilted portion not exceeding 7.2m.
• Open to sky swimming pools at terrace above topmost storey or on top of
topmost podium and ground.
• Area of service duct abutting toilets not more than 1.2m. In case of high
rise more than 70m than 2m width is allowed by commissioner.
• Glass façade / glazing not exceeding 0.3m from building line in non-
residential building.
• Servants toilet not exceeding 2.2 sqm. At staircase mid-landing and at stilt,
parking levels.
• Areas of staircase rooms, lift rooms, staircase / lift wells and passages in
stlit, basement and parking floors exclusively used for parking.
• Areas covered by staircase / lift well including lobbies as specified.
Areas to be counted in FSI DCR 35(3)

• Covered garages.
• Fire escape balcony provided in industrial building.
• A servants toilet other than mid-landing, stilt and parking levels.
• Parts/ pockets/ covered terraces except open terrace above topmost
storey or part terrace at topmost storey due to planning constraints but
accessible for common staircase.
• Area below swimming pool exceeding 1.5m for services from floor level.
• AC plant room, AHU room, meter room, DG set room other than provided
in basement.
• Fire check floor/ service floor of high exceeding 1.8m.
• Area of balconies.
• Niches below window sill.
• Area of one public booth and one telephone exchange (PBX) room per
building.
• Ornamental projections including the voids, flower bed, projecting from the
face of the building except for the terrace level.
• MTNL room.
• Letter box room on the ground floor of residential and commercial building.
• Covered areas required on terrace for antenna etc, in excess of 20sq.m.
• The parking floors in excess of required parking. Deck parking inclusive of
car lifts and passages there to on habitable floors.
• Drivers room/ sanitary block on podium and on parking floor.
• Covered swimming pool.
What is Premium FSI?

If you need to extend the allowable Floor Space Index (FSI), you have to pay
a premium fee to the govt.
To avail this FSI, the abutting road of the land must be at least 30 feet.

• 30 – 40 Feet Road Width – 20 % Premium FSI

• 40 – 60 Feet Road Width – 30 % Premium FSI
• more than 60 Feet Road Width – 40 % Premium FSI

If the land location of the building has 30 – 40 feet abutting roadway, then you
can make avail the premium FSI of 20% which means you can build 20%
more than allowable FSI.
For Example, If you have 1000 Sq.ft Land located near 30 feet road (where
normal FSI is 1.5), then you can make avail of the premium FSI 20% by
paying the premium fee. So,

Built – up Area = 1000 x Normal FSI x Premium FSI (%)

= 1000 x 1.5 x 20 %
= 1800 Sq. Ft
Difference between FSI and Fungible FSI
• The municipal corporation of Mumbai introduced this system to curb
misuse of existing building regulations by developers.
• Developers would build space over and above the allowable FSI by the
means of some grey areas in the building regulations. These grey areas
centered on things that were free of FSI, or not counted in FSI
calculations, such as flower beds, services shafts, and balconies.
• In the fungible FSI system, the allowable FSI on a plot is increased by
35%, with a maximum cap on the total construction area, with no
exemptions. This serves to reduce ‘overbuilding’ on plots by developers.
• The fungible FSI seeks to act as a replacement for or a legalization of
the misuse of regulations, but with a clear mathematical limit that should
not be exceeded. As of 2015, fungible FSI is applicable to all plots in
Mumbai with the exception of those that fall under Coastal Regulation
Zone (CRZ) limits.
Current status of FSI in Mumbai
• The Floor space index in Mumbai varies depending on the development
ensued upon. Generally an FSI of 1.5 – 1.6 is considered in the island city,
and FSI of 1 in the suburbs.
• However for redevelopment, slum rehabilitation, making common
recreational areas, construction low range apartments etc., the Government
helps compensate the builder by providing additional FSI, so that the
developer can benefit out of rehabilitating old constructions, making more
public usability areas etc.
• Developers can also buy an additional FSI by paying premium to it, so as to
build dry areas, flower beds etc.

New FSI Policy – “Mumbai’s Draft Development Plan 2034”

• The Development Plan 2034 has come up with maximum permissible floor
space index (FSI) for each plot area in Mumbai.
• Realty players have welcomed the Municipal Corporation’s proposal to
increase floor space index (FSI) up to 8 in the Development Control Rules
to be applicable till 2034.
• The permissible FSI will eventually increase as per the locations with better
infrastructure connectivity, accessibility, area’s future potential, its proximity
to transit stations and the existing levels of FSI consumed.
Which law(s) govern Floor Space Index in Mumbai?
The Development Control Regulations for Greater Bombay, 1991 defines FSI
and state its regulation.

What is the Floor Space Index FSI in Mumbai?

Section 32 of the Development Control Regulations for Greater Bombay, 1991
deals with Floor Space Indices and Tenement Density in Residential,
Commercial and Industrial Zones.
The maximum permissible Floor Space Indices and tenement densities
for various occupancies and locations and for various use zones are given in
Table 14 of the Regulations.
Floor Space Index values as per Table for New Residential Buildings

LOCATION FSI VALUE

Island City 1.33
The area earmarked for BARC from ‘M’ Ward and the areas
comprised in “N” ward bounded on the west by Eastern Express Highway; on
0.75
the North by northern boundary of ‘N’ Ward on the East by Thane Creek and
on the south by the northern boundary of N Ward.
Akse, Erangal and Marve in the P North Ward and Gorai and Manori in the R
0.5
Ward excepting gaothan proper
Remaining Suburbs and Extended Suburbs including gaothans 1.0
Advantages :
• F.S.I may be considered as a restriction but it has his own benefits in a
city or a place where construction is progressing in a huge speed.
• It maintains the ratio of open space to built space.
• It maintains the skyline line of the city.
• A average F.S.I value ensures a good development of the project.
• Maintaining equilibrium between sustained, planned growth and
development is important.

Disadvantages :
• Where, F.S.I is considered a poor predictor of physical form. With less
F.S.I values the employment and the idea of accommodating the ever
increasing population suffers.
• Therefore, with average F.S.I one must turn it into an asset and design
the end product that caters and solves all the problems.