Super Built-up Area Calculator
Start from whichever area you know and enter the loading and wall share from the builder’s documents. The super built up area calculator shows all three areas side by side and how much of the listed size is usable floor.
Super built-up, built-up and carpet area
Area definitions differ by country, authority and contract. This calculator applies the convention you choose; the area in your agreement is the one that counts.
A bare number is m²; 1200 sq ft works too
Builders state loading in different ways; pick the one your documents use.
Any currency. Leave blank to skip the price lines.
Assumptions
Change any value to match your product or local rules.
Basis: Example only. Loading and wall shares vary by project; use the figures in your builder’s documents.
Under RERA 2016 s.2(k) internal partition walls are part of carpet area, so leave them out of this share.
Basis: Example only. Loading and wall shares vary by project; use the figures in your builder’s documents.
- Super built-up area
- 111.48 m²
- 1,200.0 sq ft
- Built-up area
- 89.18 m²
- 960.0 sq ft
- Carpet area
- 80.27 m²
- 864.0 sq ft
- Carpet ÷ super built-up
- 72.0%
- Not yours alone (super built-up − carpet)
- 31.21 m²
- 336.0 sq ft
- Total price
- Not entered
- Price per unit of carpet area
- Not entered
Of 111.48 m² (1,200.0 sq ft) super built-up, 80.27 m² (864.0 sq ft) is carpet area (72.0%).
How this was calculated
- Loading on built-up: super built-up = built-up × (1 + loading); carpet = built-up × (1 − walls)
- Loading on carpet: super built-up = carpet × (1 + loading); built-up = carpet ÷ (1 − walls)
- Starting from another area runs the same lines backwards
- Efficiency = carpet ÷ super built-up
- Built-up = 111.48 m² ÷ (1 + 25.0%) = 89.18 m²
- Carpet = 89.18 m² × (1 − 10.0%) = 80.27 m²
- Efficiency = 80.27 m² ÷ 111.48 m² = 72.0%
Loading percentage calculator
Loading percentage from two areas
Area definitions differ by country, authority and contract. This calculator applies the convention you choose; the area in your agreement is the one that counts.
A bare number is m²; 1200 sq ft works too
The area your documents add the loading to.
- Loading
- 38.89%
- Added for common areas
- 31.22 m²
- 336.0 sq ft
- Carpet ÷ super built-up
- 72.0%
A loading of 38.89% on the carpet area turns 80.27 m² into 111.48 m².
How this was calculated
- Loading % = (super built-up − base) ÷ base × 100, where base is the carpet or built-up area
- Efficiency = carpet ÷ super built-up (when the base is carpet area)
- Loading = (111.48 m² − 80.27 m²) ÷ 80.27 m² × 100 = 38.89%
- Efficiency = 80.27 m² ÷ 111.48 m² = 72.0%
How the calculator works it out
Pick a starting area
Super built-up, built-up or carpet: whichever figure is on the listing or in the agreement.
Say where the loading goes
Some builders add the loading to the built-up area, others to the carpet area. The same percentage gives different results, so pick the one your documents use.
Enter the two percentages
Loading is the share added for common areas. The wall share is the part of the built-up area taken by walls and balconies. The defaults are examples only.
Read all three
The calculator runs the formulas forwards or backwards from your starting area and shows the efficiency: carpet area as a share of super built-up area.
The three areas in one picture
Picture three outlines, one inside the other. The innermost is the carpet area: the usable floor of the flat. India’s RERA Act 2016, section 2(k), defines it as the net usable floor area, excluding the area covered by external walls, service shafts, exclusive balconies or verandahs and exclusive open terraces, but including the area under internal partition walls. Around it is the built-up area, which adds the external walls and shafts (and often balconies; check your documents). The outermost is the super built-up area: the built-up area plus your share of the lobby, staircases, lift wells and other common parts of the building.
Only the carpet area can be checked with a tape measure inside the flat. The other two depend on drawings and on how the builder shares out the common areas, which is why the calculator takes their percentages as inputs instead of assuming any.
Loading factor and the two ways it is quoted
The loading (or loading factor) is the percentage added for common areas. Quoted on built-up area, super built-up = built-up × (1 + loading). Quoted on carpet area, super built-up = carpet × (1 + loading). A 25 % loading means different things in the two cases: on a 1,000 sq ft built-up area it adds 250 sq ft, while on an 864 sq ft carpet area it adds 216 sq ft.
If your documents give a loading without saying which area it applies to, ask. Running the calculator both ways shows how much the answer depends on it.
Built-up area, the middle figure
Built-up area sits between the other two. To work it out from the super built-up area, set “The area you know” to super built-up: with the loading on built-up area, built-up = super built-up ÷ (1 + loading). To work it out from a carpet area you measured, start from carpet: built-up = carpet ÷ (1 − wall share), where the wall share covers external walls, shafts and balconies. To go the other way, press “Built-up area” under “Start from” (it loads the 960 sq ft built-up figure from the example below) or set the starting area to built-up yourself, and read the carpet and super built-up figures.
Worked example: a 1,200 sq ft listing
A flat is listed at 1,200 sq ft super built-up (about 111.48 m²), with a 25 % loading on the built-up area and external walls, shafts and balconies taking 10 % of the built-up area.
Built-up = 1,200 ÷ 1.25 = 960 sq ft (about 89.19 m²). Carpet = 960 × 0.90 = 864 sq ft (about 80.27 m²). Carpet area is 864 ÷ 1,200 = 72 % of the listed size, and 336 sq ft of the listed figure is external walls, shafts, balconies and shared space. Entered as 111.48 m² in metric, the calculator gives 89.18 m² built-up and 80.27 m² carpet: 111.48 is itself rounded, so the built-up figure comes out 0.01 m² below the converted 89.19 m².
Comparing two listings by usable area
Two flats listed at the same super built-up size can have different carpet areas if their loadings differ. Enter each listing with its own loading and compare the carpet areas, not the listed sizes. If you also enter the price per unit area the listing quotes, and the area that price is quoted on, the calculator shows the price per unit of carpet area, which puts both flats on the same footing. Prices are whatever you type, in any currency; nothing is stored.
If you can visit the flat, measure it with the carpet area calculator and compare with the figure worked out here.
Frequently asked questions
How do I calculate carpet area from super built-up area?
Divide by (1 + loading) to get the built-up area, then multiply by (1 − wall share) to get the carpet area, when the loading is quoted on built-up area. When the loading is quoted on carpet area, carpet = super built-up ÷ (1 + loading). Use the percentages in your builder’s documents.
How do I calculate loading percentage?
Subtract the base area from the super built-up area, divide by the base area and multiply by 100. The base is the area your documents add the loading to: carpet or built-up. With 1,200 sq ft super built-up and 864 sq ft carpet, (1,200 − 864) ÷ 864 × 100 ≈ 38.89 %; with 960 sq ft built-up instead, the loading is 25 %.
What is loading factor?
The percentage a builder adds to a flat’s own area to cover its share of common areas such as the lobby, stairs and lift. It is added either to the built-up or to the carpet area, which is why the calculator asks which.
How is built-up area calculated?
Measured, it is the carpet area plus the external walls and shafts (the internal partition walls are already in the RERA carpet area); some definitions also include balconies, so check your documents. Worked back from a listing, it is the super built-up area ÷ (1 + loading) when the loading is on built-up area.
What percentage of super built-up area is carpet area?
It depends on the project’s loading and wall share, so no single figure applies. The calculator shows it as “Carpet ÷ super built-up” once you enter the percentages from your documents.
Which area is the price based on?
Whichever the seller or agreement says. Set “Price is quoted on” to that area and the calculator also shows the price per unit of carpet area, so you can compare listings quoted on different areas.
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