FSI stands for Floor Space Index. It is the ratio between the total floor area you are allowed to build and the size of your plot.
The formula
Buildable area = Plot area × FSI
So a 2,000 sq.ft plot with an FSI of 1.4 allows up to 2,800 sq.ft of built-up floor area across all floors.
| Plot area | FSI | Total buildable area |
|---|---|---|
| 1,500 sq.ft | 1.0 | 1,500 sq.ft |
| 2,000 sq.ft | 1.4 | 2,800 sq.ft |
| 3,000 sq.ft | 1.4 | 4,200 sq.ft |
Why buyers should care
Two plots of the same size and price can offer very different value if their FSI differs. A higher FSI means you can build more floor area, whether as extra floors or a larger footprint.
What FSI does not tell you
- Ground coverage: setbacks and open-space rules still limit how much of the plot you can cover.
- Height limits: some areas cap the number of floors regardless of FSI.
- Premium FSI: extra buildable area may be available for a fee, which changes the economics.
Compare plots on FSI, not just price
When you shortlist projects, look at the price per buildable square foot as well as the price per plot square foot. The FSI figure is shown on every project card, and the FSI calculator on the home page does the arithmetic for you.
