Floor Area Ratio (FAR)
Posted on / by Aeon-spaces / in Blog

What is Floor Area Ratio (FAR) and importance of it?

Floor area ratio (FAR) is the total floor area of a building divided by the size of the plot or parcel of land on which it stands. FAR is usually expressed as a number between 0 and 10 or 12.

A floor area ratio (FAR) is the total square feet of usable building area with allowances for perimeter columns and those portions of the building that protrude into open space areas. FAR is calculated by dividing the gross total square feet by the size of the lot without taking into account interior columns or projections onto an adjoining property. Various policies govern FAR including density, local codes, environmental concerns and omissions leftover from previous reining construction projects.

The floor area ratio is a measurement that determines the size of any building with relation to the amount of land required for construction. For example, if we take an open plot which is 1000 square meters and build something that needs 200 square meters, then its FAR would be 20. The idea behind this is so that people are able to use their land in a better way by constructing buildings on it. If there is no FAR or if the FAR is high (like in the case above) then this would encourage people to construct buildings as tall as possible and in massive quantity because they know they can use up all their space! In densely populated cities where space crunch is real , it’s important that authorities focus on accommodating a high number of people within limited available land through increasing FAR and reducing FSI ( Floor Space Index).

How to calculate Floor Area Ratio (FAR)?

The FAR or FSI is the ratio of the cumulative area of all the floors of a building to the size of the land on which the structure is built. The formula to calculate FAR is –

Floor area ratio = (Total enclosed area across floors of buildings, Gross Floor Area) / (Area of
the plot) or FAR = Total Floor Area / Size of Land

For instance, if the gross floor area of a building across three floors is 200 sq m and the plot area
is 100 sq m

FAR = 500/100 = 5
An FSI of 2 indicates that the total floor area of a building should be twice its plot size. Similarly, on a plot of 100 sq m there is room for 1 x 100 sq ft or 1,000 sq ft (1,000 sq m or 10,000 sq ft). Suppose one constructs 40 sq m on the ground floor, another 40 sq m on the first floor, then they can build only 20 or 20% of the second floor because that needs to be 80% done!

Why is FAR Important?

Floor Area Ratio is an important tool for homebuyers when determining the density of a particular area. A high Floor Area Ratio indicates a more densely built environment, while a low Floor Area Ratio indicates a more spread out or suburban environment.

It can also be used to calculate the maximum allowable height of a building. This is done by dividing the maximum Floor Area Ratio by the site’s lot coverage. For example, if a zoning district has a maximum Floor Area Ratio of 1:10 and a lot coverage of 50%, the maximum allowable height of a building on that lot would be 20 feet (10 divided by 50 equals 20).


The Floor Area Ratio (FAR) is a key consideration when it comes to planning a new construction project. For example, if you are building a single family residence, the FAR is not likely going to be a factor. However, if you are planning on building a commercial or multi-family building, FAR is going to be something that you will want to take into consideration.


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