FSI / FAR calculator — permissible built-up area from a plot
Enter the plot, the area you will surrender, and the base and premium FSI your authority permits. Get the built-up area the site can legally carry, split by entitlement.
Site
Road widening line, OSR or reservation handover, in the same unit as the plot.
Entitlement
Confirm with the sanctioning authority. DevPartner supplies no planning figure for any city.
Only the additional FSI you have confirmed you can buy or load. Enter zero if unconfirmed.
Result — calculated from your inputs
Buildable area by entitlement
Plot basis
Continue to a full site assessment
A calculator answers one question. A DevPartner assessment carries planning capacity, programme, cost, revenue, deal structure and cash flow through one deterministic model and freezes a versioned decision report.
Carried across: Site extent (1 acre); Stated base FSI (1.5). Nothing else from this page is transferred, and no opportunity is created until you save one.
How this calculator works
net plot = gross plot − surrendered area total FSI = base FSI + premium/TDR FSI built-up area = net plot × total FSI
- You enter
- A value you supply. Nothing is assumed for you.
- Calculated
- Arithmetic on your inputs, shown in the working.
- Assumption
- A factor or allowance you can change — mix ratios, wastage, dry-volume factors.
- Approximation
- Geometry or method that approximates reality; labelled wherever used.
- Verify locally
- Planning parameters, statutory rates and structural design must come from the authority or a qualified professional.
FSI is applied to net plot area, not gross
Most authorities compute permissible built-up area on the plot area remaining after road widening lines, reservations and any mandated open space reservation handover. Applying FSI to the gross parcel is the most common way an early appraisal overstates capacity, and the error compounds through every downstream number: revenue, cost, and the land price the scheme can support.
Enter the surrender explicitly. If you do not yet know it, run the calculation twice — once with zero and once with a conservative allowance — and note the spread as an open item rather than adopting the optimistic figure.
Base FSI and premium FSI are different decisions
Base FSI is your entitlement. Premium, chargeable, fungible or TDR FSI is a purchase: it costs money per square foot, it may be capped by road width or plot size, and in several states it is subject to policy that changes between master plan revisions. Treating the two as one number hides a real cost and a real risk.
This calculator keeps them separate so the built-up area attributable to paid entitlement is visible. Carry that split into your cost model — the premium payable belongs in cost, not in a footnote.
What still limits you after FSI
FSI is a ceiling, not a design. Ground coverage, setbacks, height limits tied to road width, parking provision, fire tender access, staircase and lift core requirements and unit mix can all bind before the FSI does. A site that permits 2,00,000 square feet on paper may only accommodate 1,70,000 once the envelope is drawn.
Use the ground coverage calculator to test the footprint, and the saleable area calculator to see what actually becomes sellable product.
Worked example
A 10,000 sq ft plot loses 1,000 sq ft to road widening, leaving 9,000 sq ft net. At a base FSI of 2.0 that is 18,000 sq ft of built-up area. Buying 0.5 of premium FSI adds 4,500 sq ft, taking the scheme to 22,500 sq ft at a total intensity of 2.5 on the net plot.
Notice that the deduction cost 2,000 sq ft of saleable capacity before any premium was bought. Deductions usually matter more than the premium does.
Mistakes with FSI and FAR
Applying FSI to the gross plot when the rules apply it to the net plot after surrenders and reservations.
Treating premium, chargeable or TDR FSI as automatically available. It is separately priced, separately sanctioned and often capped.
Assuming everything counted as built-up area is saleable. Services, refuge areas, parking and circulation consume a large share, and only the planning rules decide what is exempt.
This is arithmetic, not entitlement
DevPartner publishes no FSI value for any city, zone or road width. The base and premium figures are yours to obtain from the sanctioned development control regulations or your planning consultant, and the calculator simply multiplies them by the net plot.
Height limits, setbacks, ground coverage, parking, airport height clearance and use-zone restrictions all bind independently, and any one of them can make the arithmetic capacity unbuildable.
Frequently asked questions
- What is the difference between FSI and FAR?
- None in substance. Floor Space Index and Floor Area Ratio both express permissible built-up area as a multiple of plot area. Indian development control regulations use FSI more often; FAR appears in some state and central documents. A FAR of 200% is an FSI of 2.0.
- Is FSI calculated on gross or net plot area?
- Almost always on net plot area, after deducting land surrendered for road widening, reservations and mandated handovers. Some authorities also grant compensatory FSI on the surrendered portion, which is a separate entitlement — enter it in the premium field only if it has been confirmed for your site.
- Does this calculator know the FSI for my city?
- No, deliberately. FSI varies by city, zone, road width, plot size, land use and current master plan, and is revised without notice. Any published figure would be wrong for most sites. Confirm your permissible FSI with the sanctioning authority or your licensed architect and enter it.
- Does built-up area equal saleable area?
- No. Built-up area includes cores, corridors, services and other non-sellable space, while quoted saleable area applies a loading factor on top of what a buyer actually occupies. Use the saleable area and carpet area calculators to get from one to the other.