Enter the Total Floor Area and Total Area of the plot into the calculator to determine the Floor Space Index. This calculator can also evaluate any of the variables given the others are known.

Floor Space Index Formula

The following formula is used to calculate the Floor Space Index (FSI).

FSI = TFA / TA

Variables:

  • FSI is the Floor Space Index
  • TFA is the Total Floor Area (sq ft or sq m)
  • TA is the Total Area of the plot (sq ft or sq m)

To calculate the Floor Space Index, divide the Total Floor Area by the Total Area of the plot. The result is the Floor Space Index, which indicates the ratio of the total floor area that can be built upon a plot to the size of that plot.

What is a Floor Space Index?

Floor Space Index (FSI), also known as Floor Area Ratio (FAR), is a measure used in urban planning to limit the amount of construction in a certain area. It is the ratio of the total floor area of buildings on a certain location to the size of the land of that location. This index is used to control the density of buildings and prevent overcrowding in urban areas. Higher FSI values indicate higher potential for construction and development.

How to Calculate Floor Space Index?

The following steps outline how to calculate the Floor Space Index (FSI).


  1. First, determine the Total Floor Area (TFA) in square feet or square meters.
  2. Next, determine the Total Area of the plot (TA) in square feet or square meters.
  3. Next, gather the formula from above: FSI = TFA / TA.
  4. Finally, calculate the Floor Space Index (FSI).
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem:

Use the following variables as an example problem to test your knowledge.

Total Floor Area (TFA) = 5000 sq ft

Total Area of the plot (TA) = 10000 sq ft