What is the meaning of FSI?

FSI stands for floor space index. It is the ratio of a building’s total built-up area to the area of the plot it stands on. If a 100 square metre plot carries 200 square metres of floor area, its FSI is 2. Planning authorities set the maximum FSI allowed for each plot.

How is FSI calculated?

Divide the total built-up area of all floors by the plot area. For example, three floors of 80 square metres each on a 120 square metre plot give 240 ÷ 120, an FSI of 2. Local rules decide which spaces count toward built-up area, so balconies, stairs and parking may be treated differently in each city.

Is FSI the same as FAR?

Yes. Floor space index (FSI) and floor area ratio (FAR) are two names for the same measure: built-up area divided by plot area. Some regulations write it as a ratio, such as 2, and some as a percentage, such as 200%. Read the figure in the units your local zoning regulations use.

Why does FSI matter when I buy at a bank auction?

A bank sells as is where is, so any construction beyond the permitted FSI comes with the property. Excess floor area is a deviation from the approved plan. It can affect the occupancy certificate, the Khata, a lender’s valuation and enforcement by the planning authority. Compare the building with its approved plan before you pay EMD.

What should I check about FSI before I bid?

Ask the Authorised Officer for the approved building plan and the occupancy certificate. On the site visit, compare the floors and built-up area with the plan. For a flat, check the project’s RERA page. Have an advocate or architect assess any extra floor area and whether the local rules allow it to be regularised.

Title and due diligence

FSI meaning: how floor space index works and why buyers check it

Q: Who decides the FSI for a plot in Bengaluru or Hyderabad?

The planning authority does, through the zoning regulations and building rules for the area: the master plan and zoning regulations in Bengaluru, and the building rules that apply in Hyderabad. How much may be built depends on factors such as road width, zone and use, and some regulations allow extra floor area through premium FSI or transferable development rights.

By Indresh Gowda, Co-Founder, Auction Dunia

Law and portal facts checked as of 5 November 2026 · 6 min read

The short answer

FSI meaning: floor space index, also called floor area ratio (FAR), is a building’s total built-up area divided by its plot area. A 100 square metre plot with a permitted FSI of 2 can carry 200 square metres of floor area. Planning rules set the limit; a buyer checks whether the building matches its approved plan.

Key points

FSI = total built-up area ÷ plot area. FSI and FAR are two names for the same measure.
The planning authority sets the maximum FSI for a plot, and a building plan is approved against it.
Which spaces count towards built-up area depends on the local rules, so take the figure for a property from its approved plan and the current regulations.
For a buyer of an existing flat or house, including at a bank auction, the question is not how much could be built, but whether what was built matches what was approved.

FSI meaning: what floor space index is

FSI is the ratio of the total built-up area of a building, across all its floors, to the area of the plot it stands on. The local planning regulations set the maximum FSI for a plot, and a building plan is approved against it. A higher FSI allows more floor area on the same plot; a lower FSI allows less.

For a buyer, FSI is one of the things an approved plan fixes, alongside setbacks, height and use. When a building is put up with more floor area than its plan allows, the difference is a deviation, and deviations are what affect approvals, records and lending later.

How FSI is calculated

Formula

FSI = Total built-up area ÷ Plot area

For example (illustrative only), on a plot of 100 square metres with a permitted FSI of 2, the total built-up area allowed is 200 square metres. It can be spread over several floors, within the height, setback and other limits in the regulations. Which spaces count towards the built-up area, and which are excluded (for example some parking, lift and staircase areas), depends on the local rules.

Who sets FSI

FSI is set by the planning and building regulations of the authority where the property lies: the master plan and zoning regulations for Bengaluru, and the building rules that apply in Hyderabad. How much may be built usually depends on factors such as the road width in front of the plot, the zone and the use (residential or commercial). The figures change when regulations are revised, so take the applicable FSI from the approved plan and the current regulations, not from a general article.

Some regulations allow extra floor area in specific situations, such as transferable development rights or premium FSI. Whether a particular building used any of these is shown in its approved plan.

Why FSI matters when you buy at an auction

A bank sells a property “as is where is”, and the buyer receives the owner’s title with whatever goes with it. If the building exceeds its approved plan, that goes with it too. A deviation can show up in several places:

The occupancy certificate: a building that deviates from its plan may not have one, or may have one for fewer floors than were built.
The municipal record: a property without the required approvals may be recorded as B-Khata in Bengaluru, and a Khata is not title.
Lending: a lender’s valuer compares the built area with the approved plan, and deviations can reduce or hold up a loan.
Notices: unauthorised construction can attract regularisation or enforcement action by the local authority, depending on local law.

What to check before you bid

1
Get the approved plan and the OC
Ask for the approved building plan and the occupancy certificate, from the Authorised Officer or the association, and read the permitted floors and areas.
2
Compare on the inspection visit
Compare what is built with the plan: the number of floors, enclosed balconies or terraces, and any added structures.
3
Check the RERA page
For an apartment, check the project’s RERA page if it has one, for the approvals recorded.
4
Read the records together
Check the municipal record for the property’s status, and have an advocate read the approvals with the title documents.

Whether a particular deviation can be regularised, and at what cost, depends on local law and the facts, and is a question for an advocate or architect before you bid.

What the auction route cannot promise

This guide quotes no FSI figures: take the figure for a property from its approved plan and the current regulations of its planning authority.
A bank sells “as is where is”, so construction beyond the approved plan comes with the property.
Whether a deviation can be regularised, and at what cost, depends on local law and the facts.

Questions buyers ask

Sources

Statutes, rules and judgments first. Checked as of 5 November 2026; the law and portal practice change, so confirm against the source before relying on a detail.

This guide explains the law and the process in general terms. It is not advice on any specific property; that belongs in a due diligence report on the property itself.

A specific property in mind?

Tell us what you are buying it for, and we will tell you what needs checking before you pay EMD.

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