How this calculation works
Keep the same area basis for the eligible plot and the counted floor total. Multiply the plot quantity by the entered ratio, compare the supplied floor total and show the signed difference. The tool does not choose a legally permissible ratio or decide which floors count.
Ratio budget = eligible plot area × entered ratio; used ratio = counted floor area / eligible plot areaA worked example
With entered eligible plot area 1,200 sq ft and ratio 2, the ratio budget is 2,400 sq ft. A counted floor total of 1,800 sq ft uses ratio 1.5 and leaves a model difference of 600 sq ft.
Good to know
The ratio, eligible plot area and counted floor area are supplied assumptions. No current local permissible FSI/FAR, exemptions, road-width rule, coverage, height, setbacks, premium, fee or approval is determined. The reference supports the quotient definition only; its archived rules are not implemented.
Check the land-unit definitions and sources
The standard factors use the international foot and an acre of 43,560 sq ft. Cent means 1/100 acre; gunta means 1/40 acre; the selected Chennai ground means 2,400 sq ft.
The Assam report defines bigha as 14,400 sq ft, katha as 2,880 sq ft and lecha as 144 sq ft. The cited West Bengal court order mentions a 720-sq-ft katha convention. These are explicit presets, not an automatic definition for every record or every place using the same name. Match your record to the stated convention, or use its verified custom factor.
- NIST: exact international-foot and acre factors (opens in a new tab) ↗
- API Setu MDDS: acre/cent and acre/gunta relationships (opens in a new tab) ↗
- Greater Chennai Corporation: one ground is 2,400 sq ft (opens in a new tab) ↗
- Government of Assam AIRBMP framework: section 7.2, page 28 (bigha, katha and lecha) (opens in a new tab) ↗
- Supreme Court order, 7 May 2025: paragraph 2, page 2 (West Bengal katha) (opens in a new tab) ↗
The acre relationships are converted using exact base factors. Rounded or unrelated regional values in a reference table are not substituted for these definitions.
Counted floor area and plot area are different inputs
An entered FSI of 2 applied to 1,200 sq ft gives a model floor-area budget of 2,400 sq ft. That multiplication does not mean the building may cover the whole plot, reach a particular height or receive an approval. The eligible denominator and counted floor total must be supplied for the actual scenario.
If the entered counted floor area is 1,800 sq ft, dividing by the 1,200 sq ft denominator gives used ratio 1.5. Subtracting that counted area from the ratio budget leaves 600 sq ft in this arithmetic model. A negative difference means the supplied counted quantity exceeds this budget; it is not hidden by a zero floor.
The India land area converter can help express a recorded extent in a consistent area unit first. A ground-floor footprint, a whole parcel and an eligible plot denominator are not interchangeable merely because they are all areas.
A ratio budget does not identify a unique building
A total of 2,400 sq ft could be written as two equal 1,200 sq ft floor areas or four equal 600 sq ft floor areas. Those are arithmetic arrangements of the same total. This page evaluates neither arrangement for setbacks, coverage, height, access, parking or other constraints.
Changing the area unit multiplies both area inputs by the same factor and leaves the used ratio unchanged. For example, the ratio of 1,800 to 1,200 is the same as the ratio of their square-metre equivalents. Do not convert just the numerator and leave the denominator in another unit.
The reference link describes a published quotient definition in an archived rule document. No current locality limit or exclusion list is taken from that archive. In particular, the example ratio of 2 is an editable assumption, not a claim about any city’s permission.
A few questions, answered
Does the tool look up my permitted FSI?
No. You supply the ratio and eligible/countable areas. No location-specific planning lookup is made.
Can I infer the number of floors from the result?
Not uniquely. Floor area can be distributed over different footprints and floors, subject to constraints this tool does not evaluate.
Why can the difference be negative?
It is budget minus counted floor area. Keeping the sign makes an over-budget scenario visible rather than presenting zero as unused capacity.