FAR and FSI Explained: Floor Area Ratio for Buyers
FAR and FSI decide how much you can build on a piece of land. If you are buying a plot, a builder floor, or even a flat in a redevelopment project, this one number quietly controls value, density and future potential. This guide explains FAR and FSI in plain language, with real examples and the checks that matter to a buyer.
Quick summary
- FAR (Floor Area Ratio) and FSI (Floor Space Index) mean the same thing. Both are the ratio of total built-up floor area allowed to the plot area.
- A FAR of 2 on a 200 sq m plot lets you build 400 sq m of floor area, spread across floors.
- Higher FAR means more sellable area, which usually means higher land value and denser buildings.
- FAR is set by the local authority and varies by city, zone, road width and plot size. Some cities let you buy extra FAR.
What FAR and FSI actually mean
FAR is a simple ratio. You take the total floor area you are allowed to build and divide it by the plot area. Written as a formula, FAR equals total built-up floor area divided by plot area. FSI is the same ratio, just a different name used in states like Maharashtra. Delhi and most northern cities say FAR, Mumbai and Gujarat often say FSI. Do not let the two terms confuse you. They are one concept.
The number tells you the building's bulk, not its height. A FAR of 2 could be a low building covering most of the plot, or a taller, slimmer tower covering less ground. Height and ground coverage are controlled by separate rules working alongside FAR.
A worked example
Say you own a plot of 300 sq m and the sanctioned FAR is 1.5.
- Permitted floor area equals 300 multiplied by 1.5, which is 450 sq m.
- You could build 150 sq m on each of three floors, or 112.5 sq m across four floors, as long as you stay within the 450 sq m total and the separate height and coverage limits.
Now raise the FAR to 2.5 on the same plot. Your permitted area jumps to 750 sq m. That extra 300 sq m of buildable space is exactly why a higher-FAR plot commands a higher price. You are buying the right to build and sell more.
Why FAR matters to a buyer
| Situation | Why FAR matters |
|---|---|
| Buying a plot to build | Decides how much home you can legally build and sell |
| Buying a builder floor | Confirms the floors were built within the sanctioned FAR, not illegally |
| Buying in a redevelopment | Higher FAR can fund the whole project and your free flat |
| Investing in land | Rising FAR in a zone can lift land value over time |
If a builder has exceeded the sanctioned FAR, the extra floors can be treated as unauthorised construction. That is a real risk on some independent floors and small buildings. Ask to see the sanctioned plan and confirm the built area matches what the authority approved.
What decides the FAR for a plot
Local authorities fix FAR through the master plan and building bylaws. The number usually depends on:
- City and zone. Commercial and transit zones often get higher FAR than pure residential ones.
- Road width. Plots on wider roads generally get higher permissible FAR.
- Plot size. Larger plots and group housing can get different FAR than small residential plots.
- Use. Residential, commercial and mixed-use each have their own limits.
Because the rules differ so much, always check the FAR for your specific plot with the local development authority rather than assuming a citywide figure.
Purchasable FAR and TDR
Several cities allow you to build beyond the base FAR by paying for it. This purchasable or chargeable FAR lets an owner buy extra buildable area from the authority at a set rate. Separately, Transferable Development Rights, or TDR, let development potential from one plot, for example land surrendered for a road, be used on another plot. In redevelopment-heavy markets like Mumbai, purchasable FSI and TDR are central to how projects get funded. If a project's viability depends on extra FAR, confirm it is sanctioned, not merely assumed.
FAR and your carpet area
FAR is calculated on built-up area, which includes walls and some common areas, not the carpet area you actually use. So a higher FAR does not translate one-to-one into more usable space in your flat. When you compare projects, look at both the FAR of the building and the carpet area of the unit. For more on that, see our guide on carpet area versus super built-up area.
Frequently asked questions
Is FAR the same as FSI?
Yes. Floor Area Ratio and Floor Space Index are two names for the same ratio, the total permitted floor area divided by the plot area. Different states simply use different terms.
How do I calculate permitted built-up area from FAR?
Multiply the plot area by the FAR. A 250 sq m plot with a FAR of 2 allows 500 sq m of total floor area, subject to separate height and ground-coverage limits.
Does a higher FAR mean a better property?
Higher FAR means more buildable and sellable area, which usually lifts land value, but it also allows denser development. For an end-user, more density can mean more neighbours and pressure on parking and utilities.
How do I find the FAR for my plot?
Check the local master plan and building bylaws, or ask the development authority for the sanctioned FAR based on your plot's zone, road width and size. Do not rely on a builder's verbal figure.
If you are weighing a plot or a builder floor and want the FAR and approvals checked, tell us the location and we can help you confirm what is legally buildable. You can also browse current residential plots to compare.
This guide is general information, not legal or engineering advice. FAR rules and terms vary by state and city. Always verify the sanctioned FAR and plans with the local authority.
