what is FSI?

What Is FSI | Floor Space Index | How to Calculate FSI | What Is Premium FSI| FSI Full Form

What Is FSI?

FSI full form is Floor Space Index and is the ratio of the built-up space on a plot to the area of the plot is a regulation followed in the development control norms of many cities. It directly tells us about the maximum permissible floor area that can be built on a plot.

What Is FSI | Floor Space Index | How to Calculate FSI | What Is Premium FSI| FSI Full Form
What Is Floor Space Index (FSI)

Numerically, FSI is the ratio of building floor covered area to the raw area available on that plot/land.

The floor space index value is changed from place to place. It also depends on the type of building. The FSI value of a specific area is easily found in all the building bylaws for various cities and municipalities. Different cities or municipalities may have different bylaws and consequently different values.

Permissible FSI/FAR value depends on

  • Size of the plot.
  • Type of building (business building, residential apartments, etc.).  
  • The width of the adjacent road. 
  • Availability of power, water, and sewer lines.

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FSI Formula

It is regulated by the Development control regulation department of a particular location and according to the National Building Code of India.

The formula for Floor space Index caculation

Floor Space Index = (Total Floor Area of all Floors of Building / Plot Area of Building)

They will regulate the FSI value based on city zone, type of building, and other amenities. The total floor area for the building must be as per the Floor space index of the area given by the government.

How to Calculate FSI of A Building

Assume you have a land of 1000 sq.ft and you want to construct a building on that land.

First of all, you have to identify your building types, it may be

  • Residential Building.
  • Commercial Building.

From building types find the rule and regulation of FSI regarding your building type in your city.

Let’s assume FSI is 2 for a building.

what is fsi?
Floor Space Index

FSI = Area of all floors / Total Plot Area

Area of all floors = FSI x Total plot Area


1000 x 2 = 2000 Sq.ft  of floor covered area on your land.

It can be either be 2 floors of 1000 Sq.ft or 4 floors of 500 Sq.ft without affecting other municipal rules (Minimum plot extent area, Front, back, side and rear setback, parking space).

What Is 2.5 FSI?

It means, if have plot area 1200 sq ft then you build 3 floor with with 1000 sq ft floor area.

What IS 1.5 FSI?

1.5 fsi means, if have plot area 750 sq ft then you build 2 floor with with 625 sq ft floor area.

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Importance of FSI In Building Construction

FSI or FAR value impacts the value of land in an area. It helps to find out the permissible dimension of lands like the size and width, thus which can be utilized to know how much land can be utilized. FSI value doesn’t remain the same for all locations, it changes from area to area. If FSI or FAR values increased by the government, the chances of getting better utilization, housing stock, and space also go up. Ultimately, all of this contributes to the price of the property. Because, if the contractor can construct more and builder will sell more, and thus they will charge reasonable charges from the home buyer

It allows you to construct the building as per rules and regulations. If the building plan is prepared with knowledge of FSI, the approvals and NOCs will not be questioned if you the first-hand know Floor space Index.

Important terms to understand:

Paid Floor Space Index: Sometimes when builder or contractor wants to increase their FSI limit, they have to pay some fund to the municipal body to get an additional area to include with the aim to increase the overall plot area is typically termed as Paid Floor Space Index.

What Is Premium FSI?

In case, FSI is limited in your city and you want to increase FSI limit, there is one option for that and it is called Premium FSI.

So, If you are willing to increase the limit of permissible floor space index (FSI) for your project, you have to pay extra charges to the local authority as Premium FSI Fund. But, you get eligible for this option you land with must be at least 30 feet long along the road length.

  • 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

For example, if your land having 30-40 feet long roadside length, then you can utilize the option of premium FSI of 20% which means you can construct 20% more than allowable FSI.

Let Take another example,

If the area total construction area of land 1000 Sq.ft which is having 30 feet roadside length (where normal FSI is 1.5), you can take advantage of premium FSI 20% by paying the premium fee. So,

Built Up Area Calculation

Floor Space Index for Various Cities of India


In India capital city, the Floor Space Index is between 1.2 and 3.5,


The permissible Floor Space Index in the Mumbai city is 1.33 to 1.83.

The Municipal Corporation of  Mumbai allows an FSI of 2.5 for development of land parcels under MHADA and 2.5 plus incentives for redevelopment work .6

The Maharashtra govt. has approved an additional 0.5 FSI on payment of a premium.


In New Town Kolkata Building Rules, 2009, the range of FSI for residential structures in Kolkata is between 1.5 and 2.5.


Construction of residential buildings in Chennai, under Chennai Second Masterplan 2026, must conform to the FSI limit of 1.5 for ordinary residential buildings and 2 for high rise buildings.

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The permissible FSI in the central areas of Ahmadabad is 1.2 while it goes up to 1.8 for localities in the suburbs.
The permissible FAR in Ahmadabad is much lower compared to other cities of the country.


The Bengaluru is called ‘Silicon Valley of India’ is divided into three zones like the intense developed, moderate developed and sparsely developed for allocation of Floor Space Index.
In Bangalore Revised Master Plan 2015, the FSI varies from 1.75 for smaller plots to 3.35 for larger plots, with consideration of factors like area, building activity, plot size, and road width.
There are separate regulations for integrated townships as well, with 40 percent designated for residential use and rest for IT/BT related areas with FSI ranging between 2.5 and 3.25 based on road width.


Hyderabad state has not put any FSI restrictions. The municipal corporation and urban development (MA&UD) department is, however, considering the reintroduction of floor space index (FSI) norm for high-rise buildings in Telangana.


The allowable floor space index in Gurgaon ranges between 1 and 1.45, as per the official website of the Haryana Urban Development Authority.
The maximum value of FSI for industrial setups is kept at 1.25. For public buildings Construction also permission to an FSI of 1.5.


For the Border area of Delhi and UP developed area in Noida and Greater Noida which witnessed high housing demand, the value of Floor Space Index is set between 2.75 and 3.5, group housing projects are allowed a FAR of 2.75.
The industrial buildings are permitted a maximum FAR of 1.5 while commercial buildings have a maximum FAR of 4, depending on building height and ground coverage.


Pune authorities permit an FSI between 1.5 and 2.5, depending on various factors, as per the Draft Development Control Regulations for Development Plan Pune and a high FAR of 5.5 is allowed for slum.

Advantages and Disadvantages of Floor Space Index:

Advantages :

F.S.I may be considered as a restriction on construction, but it has many advantages to the city.

  • It helps to maintain the ratio of open space to built-up space in an area.
  • It ensures a clear skyline to the area.
  • Good FSI values ensure good development of the project.
  • It helps to Maintain equilibrium between sustained, planned growth and development is important.


Lower Floor Space Index leads to restrictions on the development of the city.

If the Floor Space Index is too high, then it results in a non-environment friendly and haphazard development of the city.

What is 1.5 FSI?

1.5 fsi means, if have plot area 750 sq ft then you build 2 floor with with 625 sq ft floor area.

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