Floor Space Index (FSI) | FSI Meaning, Calculation Formula & More

What is FSI in Real Estate? FSI Meaning, FSI Calculation & More

Real estate transactions be complicated, especially for new buyers and investors, in the absence of proper knowledge about the varied factors and processes involved. One such popular yet oft-misunderstood jargon is Floor Space Index (FSI), also known as Floor Area Ratio (FAR).

In this article, we will understand the FSI meaning, the FSI formula and the importance of FSI in real estate.

What is FSI?

The FSI full form in construction is Floor Space Index. It is also called the Floor Area Ratio in some areas. FSI meaning is the total usable area of all floors of a building divided by the total area of the plot of land.

It determines the total area of the floors in a commercial or residential building and the number of floors that can be built on a plot of land. In simple words, it helps decide the total area of construction that is permissible on a specific plot of land.

FSI Calculation Formula

Floor Space Index = Total Usable Area of the Floors of the Building/Total Area of the Plot of Land

How to Calculate FSI?

The FSI calculation formula allows builders and developers to calculate the legally permissible area of the property that they can construct on the given plot.

The value of FSI is decided by the local municipal corporations and will vary depending on the city or region. The prevailing FSI value can be obtained from the building by-laws of the relevant municipal corporations, municipal councils, etc.

Now, let us understand FSI calculations with an example:

A developer has a 1000 sq. ft. plot. The value of FSI, as laid down by the municipal corporation, is 2. Applying the FSI formula:

Floor Space Index = Total Usable Area of the Floors of the Building/Total Area of the Plot of Land

Here, FSI = 2 , Total Area of the Plot = 1000 sq ft.

Thus, 2 = Total Usable Area of the Floors of the Building / 1000

Total Usable Area of the Floors of the Building = 1000 x 2 = 2000 sq. ft.

This means the developer can build a total area of 2000 sq. ft. on the 1000 sq. ft. plot. It can either be two floors of 1000 sq. ft. each or 5 floors of 400 sq. ft. each, or 10 floors of 200 sq. ft. each.

Know that this is a very basic FSI calculation for the sake of simplicity and understanding. In reality, there are multiple factors that impact FSI and the permissible area of construction on a plot of land.


What are the factors that impact FSI in construction?

  • Type of the building (commercial/residential)
  • Size of the plot
  • Location of the plot
  • Amenities and facilities provided (power, water, sewer lines, etc.)

Apart from these, FSI can vary depending on additional amenities, such as lifts, shafts, driveways, porches, service areas, parking, etc. For example, the FSI calculation does not include stilt or basement parking. However, in certain regions, covered parking can be a part of the FSI calculation.

What is Premium FSI in Real Estate?

In case there is a road adjoining the plot for construction, the developers/builders can ‘buy’ an additional FSI from the government by paying fixed, predetermined charges. This additional FSI is called Premium FSI. The percentage of premium or additional FSI permissible ranges from 20% to 40%, depending on the width of the adjoining road.

What is importance of FSI in Real Estate?

The government determines the FSI in construction to ensure the planned development of metro cities, to control the level and quality of construction and ensure a sustainable, spacious and well-ventilated construction.

What is FSI full form in real estate?

FSI stands for Floor Space Index.

Disclaimer: This article is based on the information publicly available for general use. We do not claim any responsibility regarding the genuineness of the same. The information provided herein does not, and is not intended to, constitute legal advice; instead, it is for general informational purposes only. We expressly disclaim any liability, which may arise due to any decision taken by any person/s basis the article hereof. Readers should obtain separate advice with respect to any particular information provided herein.

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