FSI and FAR: The Planning Rule Behind Your Bengaluru Project
The floor space index, or FAR, decides how much can be built on a plot, and it shapes the density and compliance of your project. Here is what FSI means, how it is calculated, and what a Bengaluru buyer should check.
A Bengaluru buyer comparing two apartment projects on similar plots off Sarjapur Road in September 2026 could not understand why one had far more flats than the other. The answer was the floor space index, the planning rule that decides how much can be built on a plot. One developer had more permissible floor area to work with, so more homes, while the other left more open space. For a buyer, the floor space index quietly shapes density, open space, and whether a building is even compliant, which is why it is worth understanding before you fall for a project.
The short answer. The floor space index, or FSI, also called the floor area ratio, or FAR, is the ratio of a building total built up floor area to the plot area, and it is set by the local development authority. An FSI of 2.0 on a 1,000 square foot plot permits 2,000 square feet of total built up area across all floors. The trade off for a buyer is that a higher FSI can mean more homes and higher density on the same land, while a project that quietly exceeds the permitted FSI is a compliance risk, so you check the sanctioned plan and the permissible FSI rather than assume.
What is FSI or FAR?
FSI and FAR are two names for the same planning metric: the ratio of a building total built up floor area to the area of the plot it sits on. FSI, or floor space index, is the term more common in Bengaluru and Mumbai, while FAR, or floor area ratio, is used in Delhi and internationally, but they mean the same thing. The metric tells you how intensively a plot can be built up, so a higher figure allows more floor area on the same land, and a lower figure allows less.
It is a control rather than a target. The local authority fixes the maximum FSI for a plot, and a building must stay within it, so FSI is the ceiling on how much floor area can be created on that land. Understanding it lets you read a project the way a planner does, in terms of how much has been built relative to what the plot allows.
The reason authorities use FSI at all is to manage the pressure a growing city puts on land and services. If builders could put unlimited floor area on every plot, roads, water, and drainage would be overwhelmed and open space would vanish, so the FSI is the lever that keeps built density in some relation to the infrastructure around it. That is why the permissible figure is higher near wide roads and transit corridors, which can carry more people, and lower on narrow interior lanes that cannot.
How is FSI calculated?
FSI is calculated by dividing the total built up floor area of the building by the area of the plot. So if a plot is 1,000 square feet and the permitted FSI is 2.0, the building may have up to 2,000 square feet of total floor area across all its floors combined. The floors can be arranged in different ways, but the total floor area they add up to is capped by the FSI applied to the plot. The table shows how the permissible built up area changes with the FSI on a sample plot.
| FSI on a 1,000 sq ft plot | Permissible built up area |
| FSI 1.0 | 1,000 square feet |
| FSI 1.5 | 1,500 square feet |
| FSI 2.0 | 2,000 square feet |
| FSI 2.5 | 2,500 square feet |
| FSI 3.0 | 3,000 square feet |
Who sets the FSI in Bengaluru?
In Bengaluru the FSI is set and enforced by the city and development authorities under the state building rules and the master plan, and it varies with the zone, the road width, and the plot. Broadly, permissible FSI in the city commonly falls in the region of 1.25 to around 3.25, and it can be higher along metro and transit oriented development corridors where additional floor area is allowed, sometimes through a premium floor area ratio that a developer pays for. Because these figures depend on the specific location and are revised through planning rules, the permissible FSI for a given plot is something to confirm from the authority and the sanctioned plan rather than to assume from a general range.
The road width point is worth noting, because a wider access road often permits a higher FSI, which is one reason projects on main roads can be built more intensively than those on narrow interior lanes. For a buyer, the takeaway is that the FSI is not a single citywide number but a plot specific limit, so the right question is what FSI applies to this plot and whether the building respects it.
Why does FSI matter to me as a buyer?
FSI matters because it shapes the density and the open space of the project you are buying into, and because a building that exceeds its permitted FSI carries a compliance risk. A higher FSI can mean more flats, more residents, and less open space per home, while a lower FSI can mean a less dense, more open development. Neither is simply better, but knowing the FSI helps you understand what you are actually buying, from the crowdedness of the project to the amenities that fit on the land.
The compliance angle is the sharper one. A project built beyond its sanctioned FSI can face regularisation issues, and unauthorised extra floors are exactly the kind of deviation that can leave a property as a B khata rather than an A khata, as we explain in our guide on A khata versus B khata. So the FSI is not an abstract planning number, but something that connects directly to whether your specific building is compliant and financeable.
How does FSI relate to the area I am sold?
FSI governs the total floor area a builder can create, while the area you are sold, such as super built up area, is how that floor area is packaged and priced for you, so the two are related but not the same. The FSI sets the ceiling on floor area for the whole project, and within that the developer designs the flats and the common areas, then sells you a figure that may include a share of common space. Understanding both lets you separate the planning limit from the pricing convention, which we cover in our note on carpet area versus super built up area.
For a specific project, such as Adarsh Tropica Phase 2 on Sarjapur Road, a buyer would look at the density and the open space as signs of how the available floor area has been used, and would confirm that the built area sits within the sanctioned plan. Reading the FSI alongside the area you are quoted gives you a fuller sense of both the project character and its compliance.
What should I actually check?
Check the sanctioned plan and the approvals to confirm the building respects the permissible FSI for its plot, rather than relying on a brochure. Ask for the sanctioned plan and the approval documents, and confirm that the built area, the number of floors, and the layout match what was approved. Where a project has clearly added floors or area beyond what the plot allows, treat that as a serious compliance flag and get it examined before you commit, because unauthorised construction is difficult and sometimes impossible to regularise.
You do not need to become a planning expert to do this. Asking the right questions, whether the FSI is within limits, whether the plan is sanctioned, and whether the occupancy certificate has been granted, and having a professional verify the answers, is enough to protect you. The FSI is one thread in that check, and pulling on it early tells you a great deal about whether a project is built on solid regulatory ground. We looked at this topic in an earlier explainer as well, and the underlying rule has not changed even as the corridors and premium options evolve, so the discipline of checking the sanctioned plan against the permitted figure remains the same whatever the headline numbers for a given year.
A seven step FSI check
Use this when evaluating a project.
- Ask what FSI applies to the plot under the local rules.
- Confirm the figure with the authority and the sanctioned plan.
- Check that the built area stays within the permitted FSI.
- Note whether extra area came through a premium floor area ratio.
- Watch for added floors or area beyond the sanctioned plan.
- Read the FSI alongside the density and open space you see.
- Confirm the occupancy certificate and approvals before you commit.
Frequently asked questions
What is the difference between FSI and FAR? There is none in substance. FSI, or floor space index, and FAR, or floor area ratio, are two names for the same metric, the ratio of a building total built up floor area to the plot area. FSI is the common term in Bengaluru and Mumbai, while FAR is used in Delhi and internationally.
How do I calculate the permissible built up area from FSI? Multiply the plot area by the permitted FSI. On a 1,000 square foot plot with an FSI of 2.0, the building may have up to 2,000 square feet of total floor area across all floors. A higher FSI allows more floor area on the same plot, and a lower FSI allows less.
Who decides the FSI for a Bengaluru plot? The city and development authorities set and enforce the FSI under the state building rules and the master plan, and it varies with the zone, the road width, and the plot. Because it is plot specific and revised through planning rules, confirm the permissible FSI from the authority and the sanctioned plan.
Why should a buyer care about FSI? FSI shapes the density and open space of the project and signals compliance. A building that exceeds its sanctioned FSI carries a regularisation risk, and unauthorised extra area can leave a property as a B khata, affecting your loan and resale, so checking the FSI against the sanctioned plan protects you.
Last updated 2026-09-20. PropNewz Team.
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