FSI is the abbreviation of the Floor space index, Whilst FAR is for Floor area ratio.
Floor Space Index is defined as ratio of total carped area or total floor area of a building to the area of land on which building stands.
Calculation of floor space Index
Let’s take an example. Suppose we have a four storied building with following data.
Area of ground floor = 140 m2
Area of first floor = 140 m2 (same as above)
Area of second floor = 80 m2 (due to setback)
Area of third floor = 80 m2
And area of land on which building stands is 300 square meters.
Here we have total floor area is 140 * 2+ 80 * 2= 440 square meters.
Now we will divide total floor area with the land area.
In this case