How this calculation works
An uplift on the base and a share of the quoted total use different denominators. Choose the convention before calculating or reversing the relationship. Base/quoted labels are arithmetic placeholders and do not measure a legally defined carpet or built-up area.
Base uplift p: quoted = base × (1+p); quoted share q: quoted = base / (1−q)A worked example
A 25% uplift on 900 sq ft adds 225 and gives 1,125 sq ft. The addition is 20% of that quoted total. If 25% instead means a share of the quoted area, the same base produces 1,200 sq ft.
Good to know
An entered-percentage relationship, not an official carpet/built-up/super-built-up measurement. No common-area allocation, wall measurement, statutory definition, agreement term or project disclosure is verified. Quoted-area share must be below 100%; zero-area percentage ratios are explicitly undefined.
Reference: NIST: exact international-foot and acre factors (opens in a new tab) ↗
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.
A percentage needs a named denominator
Start with 900 sq ft as a supplied base. A 25% uplift on that base adds 225 sq ft and produces 1,125 sq ft. The added 225 is only 20% of 1,125, so describing the same addition as 25% of the quoted total would be a different relationship. The model’s base/quoted efficiency is 900/1,125 = 80%.
If the addition is instead 25% of the quoted area, the base is 75% of the quote. Divide 900 by 0.75 to obtain 1,200 sq ft, with an added 300 sq ft. The two choices share a typed percentage but do not share a denominator.
The percentage calculator explains an ordinary percentage of a supplied amount. This tool adds both denominator conventions, their inverse operations and side-by-side base/quote/addition outputs so that the relationship remains visible.
Reverse the multiplier instead of subtracting the uplift
Given a quote of 1,125 sq ft and a 25% base uplift, divide by 1.25 to recover 900 sq ft. Subtracting 25% of the quote would leave 843.75 sq ft, because that subtraction uses the wrong base.
A loading percentage does not measure walls or common areas. It also does not establish a legally defined carpet, built-up or super built-up quantity. Enter base and quoted labels according to the actual relationship you intend to compare, retaining the underlying measurements and terms.
At zero loading the two modeled quantities agree. At zero starting area both modeled areas are zero, but percentage ratios with a zero denominator are undefined. A quoted-area addition share of 100% would leave no positive base fraction and is therefore rejected.
A few questions, answered
Does a 30% loading always mean the same area increase?
No. Confirm whether 30% divides by the base or the quoted total. This choice changes the multiplier.
Can this derive certified carpet area?
No. It reverses a supplied arithmetic assumption. It does not perform a measured or legally defined area assessment.
Why can a base uplift exceed 100% while a quoted share cannot?
An addition can exceed the base. An addition that consumes 100% of the quoted total leaves a zero base fraction and cannot be inverted into a finite positive quote from a positive base.