FSI (Floor Space Index): Meaning, Calculation & Importance!

June 14th, 2022


FSI (Floor Space Index), also known as FAR (Floor Area Ratio), is one of the most important elements of real estate. FSI refers to the maximum permitted area on a piece of land for construction. The FSI is the ratio of floor area covered to the available land area. FSI, which is usually set based on the National Building Code, is regulated by the municipal or local authorities of the state government. The National Building Code of India provides guidelines for building construction activities across the country.

The attractiveness of the location and its population density can be understood through the FSI. Also, even from an environmental standpoint, it is extremely crucial to know the FSI. Homebuyers must consider this because there are usually fewer open spaces if the FSI is high.

What is FSI?

FSI and FAR means the same thing but is denoted differently. For example, A FAR is expressed in decimals, while an FSI represents a percentage. The FSI can vary from one city to another and even from one locality to another within a particular city. In fact, FSI can vary even in the same location, based on the number of floors of the building. FSI is regulated based on city zone, type of building, and other amenities.

Before the construction of any project, builders are expected to furnish details of the proposed building to the respective zone for approval. These details include whether it is a residential or commercial building, the height and structure of the building, the area of land that it will be built on, etc.

Several factors directly impact the FSI – location being the primary. In locales where there is a metro, the FSI is usually higher due to the lack of space. However, FSI could be low in rural areas because of the sheer volume of land that is available for construction.

The higher the size of the plot, some municipal authorities calculate higher FSIs. Any plot adjacent to a road will have a higher FSI due to the width of the road. With the total built-up area and the plot area, you can determine the FSI using a simple formula.


Must Read: Understand Carpet Area, Built-up Area, & Super Built-up Area 

FSI Formula 

In order to calculate the Floor Area Ratio (FAR) or Floor Space Index (FSI), you need the total floor area of every floor as well as the total area of the plot of land. It can then be calculated by:

FAR = Total Floor Area of all Floors of the Building/Plot area

FSI = Total Floor Area of all Floors of the Building/Plot area x 100

If the FAR is lesser than 1, it indicates that the whole plot is usable. If the value is lower than 1, then it indicates that a portion of the land is empty – without construction. However, if the FAR value is above 1, then it means that there are multiple storeys on the same plot.

FSI Calculation

Let’s assume that you have a 1000 sq. ft. plot on which you want to build a 2000 sq. ft. structure. Then by the formula mentioned above:

FAR= 2000 / 1000

FAR = 2

If the FAR value is 2, then in FSI, it is 200%. This means they can construct 2000 sq. ft. in a 1000 sq. ft. plot.

Also, when the municipal council determines the FSI of a particular locality, it considers the road width too, among other aspects.

Importance of FSI:

The FSI value impacts the value of land in a particular locality. This value helps determine how much of the land can be used and whether the building can be multi-storeyed. FSI value doesn’t remain the same for all locales, it changes from area to area and is also different from one building to another depending upon the number of floors.

With the FSI in place, the planning and development of cities become uniform since it can ensure disciplined construction in all sectors such as railway stations, commercial and residential buildings, etc., to adhere to timelines. This can offer a clear distinction between construction space and open spaces. Furthermore, no unauthorized construction can take place.

For builders, higher FSI means they can construct more and therefore sell more, hence the affordability factor also comes in. This will come in handy in locations where there is a dire need to provide housing for all. A lower FSI would mean that a lesser area will be used for construction on that plot of area. The builder is not subject to questions regarding NOCs if the building is constructed as per the FSI.

What is Premium FSI?

Premium FSI comes into the picture when the FSI is low in your locale but you’re looking to increase the limit. To increase the limit from the permissible FSI, you would have to pay extra charges to the local authority. This charge is known as the Premium FSI Fund. The premium FSI is only applicable if the adjoining road of the land is at least 30 feet wide.

Assuming that there is a 30-40 feet wide road adjacent to the plot, then you can avail a premium FSI of 20%. This means that you can build 20% more than the permissible FSI. Likewise, if there is a 40-60 feet wide road adjacent to the plot, then you can avail a 30% premium FSI. And for plots that are abutting with over 60 feet of road, then the Premium FSI is 40%.

Width of the Road Adjacent to the Plot

Premium FSI

30-40 ft. 20%
40-60 ft. 30%
Over 60 ft. 40%

How to Calculate Premium FSI?

If you have a 2000 sq. ft. land and the FSI/FAR is 2, you can build 4000 sq. ft. on that plot. If this plot is adjacent to 50 feet wide road, then you are eligible to avail of 30% Premium FSI. This means you can build 1200 sq. ft. more than the already permissible 4000 sq. ft. With this, you can now build up to 5200 sq. ft. on the plot.

Let’s assume you have a 1000 sq. ft. land along a 70 ft. road, and the FSI/FAR is 1.5. With this FSI/FAR being 1.5, you could have built 1500 sq. ft. on the 1000 sq. ft. plot. Since it is close to a road that is 70 ft. wide, you are now eligible to avail of a premium FSI of 40%. This means that you can build an additional 600 sq. ft. on the same plot. Hence, in this situation, you can build up to 2100 sq. ft. on the plot of 1000 sq. ft.

FSI/FAR for Various Cities of India



Bengaluru has three categories of localities – Intensely Developed, Moderately Developed, and Sparsely developed. Depending on this category, plot size, and road width, the FSI/FAR can vary between 1.75 to 3.35.


The coastal city of Chennai sees the FSI/FAR value of 1.5 to 2, under the Chennai Second Master Plan, 2026. 2 is assigned to High-rises, and 1.5 to Ordinary, Low-rise buildings.


The national capital has not imposed FAR on group housing. According to the Delhi Master Plan 2021, the FSI/FAR is between 1.2 and 3.5. The governing body allows a higher value for plots that have a direct impact due to the metro. Redevelopment projects have a value of 4.


The Haryana Urban Development Authority assigns a value of 1 and 1.45, with the maximum permissible FSI/FAR for industrial setup being 1.25.


The FSI/FAR value ranges between 1.2 and 1.8 in Ahmedabad. 1.2 is kept within the central localities, and for locales in the outskirts, the value is 1.8.


The permitted FSI/FAR in Pune is between 1.5 and 2.5, as per the Draft Development Control Regulations for Development Plan. However, Pune authorities do allow the FAR to go up to as high as 4 and 5.5 for slums.


Mumbai is divided into two – the Island city and the Suburb. The former has a FSI/FAR of 1.33 and the latter has a FSI/FAR between 0.5 and 1. The developing plots under the Maharashtra Housing and Area Development Authority have a value of 2.5.


Hyderabad is the only city with no cap on the FSI value. With the average being anywhere between 6 and 7, the city is eligible to optimize as much land space as it possibly can.


Kolkata permits a FSI/FAR of 1.5 and 2.5 under the New Town Kolkata Building Rules, 2009. This, of course, depends on the land use, road width, and density of the plot of land.


What is 1.5 FSI?

FAR of 1.5 is denoted as an FSI of 150%. If you have a 1000 sq. ft. Plot/land. Then, using the formula: FSI = Total Floor Area of all Floors of the Building / Plot area. Then, FSI 1.5 = Total floor area / 1000 Total floor area = 1.5 x 1000 You can build up to 1,500 sq. ft. on that plot. You could choose to build 2 floors of 750 sq. ft. each or 3 floors of 500 sq. ft. each.

What is 2.5 FSI?

If the FSI is 2.5 and you have a 1000 sq. ft. plot: Then, using the formula: FSI = Total Floor Area of all Floors of the Building / Plot area, Similarly, 2.5 = Total Floor Area of all Floors of the Building / 1000 Total Floor Area of all Floors of the Buildings = 2.5 x 1000= 2500 You can build up to 2500 sq. ft. on that plot.

What is FSI in Construction?

FSI is the abbreviation for Floor Space Index. It is also known as Floor Area Ratio. This is the maximum permissible area that a builder can construct on a particular plot of land. The FSI value depends on various factors and is set by the municipal authorities of the state government.

What factors does FSI depend on?

The FSI value depends on many factors based on the bylaws of the city’s governing authority. It also depends on the size of the plot, the location, width of the adjacent road, availability of power, sewer lines, water, and also the type of building – commercial, residential, worship, institutional, etc.

Is Car Parking Included in FSI?

Common areas, Interior Open Spaces, Parking areas, and Basements completely used for Parking are all excluded from the FSI Calculation.

Is Balcony Included in FSI?

Balconies, terraces, lifts, and lobbies are not technically covered under the carpet area; hence they are excluded from FSI. However, it will be included if the staircase is located inside the apartment.

What is the difference between TDR and FSI?

While FSI stands for Floor Space Index, TDR stands for Transfer of Development Rights. The latter is obtained from the owner, in the form of certificates. The owner can then subsequently use these certificates to trade in the market for cash.

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