FSI calculator
Floor space index limits how much you can build on a plot. Enter your plot and the FSI to see the permitted built-up area.
Illustrative arithmetic only. The permitted built-up area for your plot is set by the planning authority.
How this is worked out
- Permitted built-up area = plot area times FSI.
- Ground floor footprint = plot area times the ground coverage percentage.
- Floors = permitted built-up area divided by the ground floor footprint.
- The FSI and the coverage are your inputs; this tool does not know the rules for your plot.
What FSI is
Floor space index (FSI), also called floor area ratio, is the total built-up area permitted divided by the plot area. An FSI of 1.5 on a 2,400 sq.ft plot permits 3,600 sq.ft of built-up area across all floors.
How to use it
- Enter the plot area in square feet.
- Enter the FSI that applies to your plot. Ask the planning authority; it depends on the zone, the road width and the use.
- Enter the ground coverage allowed after the setbacks.
- Read the permitted built-up area and how many floors of that footprint it gives.
A worked example
A 2,400 sq.ft plot with an FSI of 1.5 permits 3,600 sq.ft. With 60% ground coverage the ground floor is 1,440 sq.ft, so the permitted area is about 2.5 floors of that size.
Check the rules
FSI, setbacks, height limits and any premium FSI depend on the rules in force for your plot. Confirm them with the planning authority or your architect before you plan the design.
Questions about this tool
From the planning authority for your area, or from your architect. It depends on the zone, the road width and the type of use.
Rules differ on what is counted. Ask your architect which areas are excluded under the current rules.
No. Ground coverage is the share of the plot the building can cover at ground level. FSI limits the total area across all floors.
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