FSI (Floor Space Index), also called FAR (Floor Area Ratio), is the ratio of the total built-up floor area you are allowed to construct to the plot area. FSI 1.8 on a 1,000 sq ft plot allows 1,800 sq ft of total built-up area across all floors.

How do I calculate the buildable area on my plot?

Multiply the plot area by the sanctioned FSI. For a 2,400 sq ft plot with FSI 2.25, the permissible built-up area is 2,400 × 2.25 = 5,400 sq ft, spread across the allowed number of floors.

Is FSI the same everywhere in India?

No. FSI is set by each city or development authority and varies by zone, road width and building type — commonly 1.0 to 2.7 for plotted housing, higher on wide roads or TOD zones. Always confirm the exact value with your local authority before planning.

FSI Calculator

Enter your plot area and the sanctioned FSI / FAR to instantly see the maximum permissible built-up area you can construct. Add a ground-coverage percentage to estimate the building footprint and number of floors. Tap a common FSI value to start.

Plot area Unit FSI / FAR Ground coverage % (optional)

2,000 sq ft × FSI 1.8 = 3,600 sq ft built-up

Built-up area (sq ft)3,600

Built-up area (sq m)334.45

Ground footprint (sq ft)—

Approx. floors—

Footprint and floors appear when you enter a ground-coverage %. Indicative only — JavaScript required.

The FSI formula

FSI (Floor Space Index), also called FAR (Floor Area Ratio), caps the total floor area you can build relative to the plot:

Max built-up area = Plot area × FSI

So a 2,000 sq ft plot with an FSI of 1.8 permits 3,600 sq ft of total built-up area across all floors. If your zone also has a ground coverage limit (the share of the plot the footprint may occupy), the rough number of floors is FSI ÷ ground-coverage ratio — e.g. FSI 1.8 with 50% coverage ≈ 3.6, so about 3–4 floors.

Typical FSI values in India

Context	Typical FSI / FAR
Plotted residential (narrow road)	1.0 – 1.2
Plotted residential (wider road)	1.5 – 1.8
Urban residential / apartments	1.8 – 2.7
TOD / metro corridor / commercial	2.7 – 4.0+

Accuracy note

FSI/FAR, ground coverage, setbacks, height limits and chargeable/free-of-FSI areas are set by your local development authority (e.g. AUDA, GUDA, DTCP, municipal GDCR) and vary by zone, road width, plot size and building use. This calculator gives the headline plot area × FSI figure and an indicative floor estimate; it does not account for premium/chargeable FSI, balcony or staircase exclusions, or setback-reduced footprints. Always confirm the sanctioned figures with the authority or your architect before planning or buying.

Frequently asked questions

What is FSI / FAR?

FSI (Floor Space Index) = FAR (Floor Area Ratio) is the ratio of total permissible built-up floor area to plot area. FSI 1.8 on a 1,000 sq ft plot allows 1,800 sq ft of built-up area across all floors.

How do I calculate buildable area on my plot?

Multiply plot area × sanctioned FSI. A 2,400 sq ft plot at FSI 2.25 = 5,400 sq ft of permissible built-up area.

What is the difference between FSI and ground coverage?

FSI limits the total area across all floors; ground coverage limits the ground-floor footprint. Floors ≈ FSI ÷ ground-coverage ratio.

Is FSI the same across India?

No — each authority sets it by zone, road width and use. Plotted housing is commonly 1.0–2.7; confirm your exact value locally.

Know the FSI? Now let buyers see every plot in 3D.

Plotex turns your 2D layout or PDF into an interactive 3D viewer showing each plot's size, facing and availability — shared on one WhatsApp link, with built-in lead capture. No CAD skills needed.

See your plot layout in 3D — free →