Home Buying

Floor Space Index (FSI) Importance and Calculation

25 NOV 2022

Among the most important aspects of real estate is Floor Space Index (FSI), sometimes known as the Floor Area Ratio (FAR). FSI refers to the maximum area of a piece of land that will be used in development. FSI is the ratio of floor area covered out of available land.

The local regulatory bodies or authorities set the FSI, which is typically set based on the Code of Building. The National Building Code of India usually gives guidelines for the construction of buildings.

The FSI can be used to comprehend the location’s desirability and population density. 

Furthermore, understanding the FSI is vital, even from an environmental perspective. Because there are typically fewer open places if the FSI is high, homebuyers must take this into account. 

Understanding FSI and FAR

FAR and FSI have the same meanings but are expressed differently. For instance, a FAR is a decimal expression, whereas an FSI is a percentage. The FSI might differ from one city to the next and even within a single city from one locality to another. Depending on the number of stories in the building, FSI might change even within a single location. FSI is controlled by city zone, building type, and other features. 

Before beginning any project, contractors must submit plans for the planned building for approval to the appropriate zone. These specifics include whether the construction will be residential or commercial, its height and structure, the size of the plot of land it will be built on, etc.

The location is the main aspect that directly affects the FSI. The FSI is typically greater in areas with metros because of the constrained space. However, due to the enormous amount of land accessible for construction, FSI may be low in rural locations. 

Some municipal authorities calculate greater FSIs based on land size. Due to the width of the road, any plot close to one will have a higher FSI. The FSI can be calculated using a straightforward calculation utilizing the total built-up area and the plot area. 

Floor Space Index (FSI) Formula

The floor area of each floor and the area of the land plot are required to compute the Floor Area Ratio (FAR) or Floor Space Index (FSI). Then, it can be estimated using the following: 

FAR = Total Floor Area of All Floors of the Building/Plot Area 

FSI = Total Floor Area of All Floors of the Building/Plot Area × 100 

If the FAR equals 1, the whole plot area can be used according to this metric. If FAR is below 1, the land is underdeveloped in multiple locations. Again, the build-up has multiple stories if FAR is greater than 1. 

Floor Space Index (FSI) Calculation 

Assume you wish to construct a 2000-square-foot building on a parcel of property that is 1000 square feet. Using the formula mentioned above, then: 

=> FAR = 2000/1000

=> FAR = 2

In FSI, the value is 200% if the FAR value is 2. This indicates that they can build 2000 square feet on a land of 1000 square feet.

In addition, the municipal council considers the road width and other factors when determining the Floor Space Index (FSI) of a certain locality. 

Importance of Floor Space Index (FSI)

The FSI value influences the value of land in a certain area. Therefore, this value influences whether and how much land can be used for a structure. The FSI value varies from location to location and depends on the number of stories in each building. Hence it is only constant across some locations. 

The FSI ensures disciplined construction in all sectors, including railroad stations, commercial and residential structures, etc., to comply with schedules, making city planning and development more uniform. This can help to distinguish clearly between open spaces and construction zones. 

Additionally, no unlawful development is permitted. 

Affordability also enters the picture because higher FSI allows builders to build more and sell more. This will be useful in areas where housing for everyone is desperately needed. A lower FSI indicates that less of that plot of land will be used for development. If the FSI constructs the structure, the builder is not subject to inquiries regarding NOCs. 

Advantages of Having FSI in Cities

F.S.I. may be considered a limitation, although it offers advantages in cities or other places where construction is moving very quickly. 

  1. It keeps the proportion of constructed to open space constant.
  2. As a result, it keeps the city’s skyline intact.
  3. An average F.S.I value guarantees the project’s successful development.
  4. Therefore, it is crucial to maintain a balance between development and planned, steady expansion.

Disadvantages of FSI

F.S.I. is viewed as a poor predictor of physical shape there. Therefore, employment and the idea of accommodating the constantly growing population suffer from lower F.S.I values.

Therefore, one must use average F.S.I as a strength and create a finished product that addresses and resolves all the issues.


The maximum floor area that can be built on a specific plot is determined by the floor space index, often known as the floor area ratio. It is based on various variables, including amenities, building type, and city zone categorization. 

The developer must adhere to the pre-determined government-approved floor space index throughout construction. The floor space index/ area ratio substantially affects the overall cost of the structure. FSI is affected by numerous variables, including building style, lot size, location, and other features. 

We hope this article has given you enough information regarding the floor space index, its contributing variables, and how it affects builders. 


Author - Confident Group

As the most trusted real estate brand in the nation, we at Confident Group strive to create a positive, smooth and transparent medium for potential home buyers with anything and everything related to home purchase. We provide informative and engaging articles which cover useful details across many verticals from the real estate sector. Our 2-decade long expertise in building infrastructure projects across Kerala and abroad backed by the trust of over 10,000 customers earned us the reputation of being the best as a real estate brand in Asia. We hope that our blogs will help in translating our experience for the prospective buyers who are looking for their dream home.


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