Carpet Area vs Built-Up vs Super Built-Up: What You Actually Pay For
UrbanYardz Editorial · Buying · 2026-06-19
Carpet area vs built up area explained for India 2026 — what RERA mandates, how loading works, and how to verify the usable space you actually pay for.
When you buy a home in India, the "size" printed in the brochure and the space you can actually use are rarely the same number. Understanding carpet area vs built up area — and the inflated super built-up area on top — is the single biggest protection against overpaying. This guide breaks down all three measures, what RERA 2016 mandates, how the loading factor quietly inflates your price, and how to verify the usable space before you sign anything.
The Three Area Definitions, Plainly
These three terms describe progressively larger slices of space, and builders love to blur them.
| Measure | What it includes | What it excludes | | Carpet area | Net usable floor inside the flat — bedrooms, hall, kitchen, internal passages, internal walls (per RERA) | External walls, shafts, balconies, common areas | | Built-up area | Carpet area + thickness of external walls + balcony/utility | Common areas like lobbies, lifts, stairs | | Super built-up area | Built-up area + your proportionate share of common areas (lobby, lift, staircase, club, corridors) | Nothing is excluded — this is the largest figure |
Carpet area is the space you live in. Built-up area is usually about 10–15% larger than carpet. Super built-up can be 25–40% larger than carpet, because it loads a share of every shared space onto your flat.
What RERA 2016 Actually Mandates
This is the most important rule for any buyer. Under the Real Estate (Regulation and Development) Act, 2016 (RERA 2016, Section 2(k)), carpet area is the defined, legally enforceable basis for selling a flat in a RERA-registered project. RERA defines carpet area as the net usable floor area within the walls of the apartment, including internal partition walls, but excluding external walls, areas under services shafts, exclusive balconies, and common areas.
In practice, this means:
- A developer of a registered project must disclose carpet area in the sale agreement and on the state RERA portal.
- They cannot legally price or sell purely on super built-up area for a RERA-registered project.
- The carpet area in your agreement is what the RERA authority will hold the builder to if you complain.
That said, builders can still *quote* a price per square foot on super built-up area in marketing material. The legal sale basis is carpet, but the headline rate you see in an ad may not be. Always trace the number back to the RERA carpet figure. (RERA is a central law administered state-by-state — confirm your project's status on your own state RERA portal, as registration details and timelines vary by state as of 2026.)
The Loading Factor: Where Your Money Quietly Goes
"Loading" is the percentage by which super built-up area exceeds carpet area. It is the developer's way of charging you for common amenities.
The formula is straightforward:
> Loading factor (%) = ((Super built-up − Carpet) ÷ Carpet) × 100
A loading of roughly 20–30% is common across Indian metros as of 2026, though this varies by city, developer and project type — luxury projects with large clubhouses, infinity pools and grand lobbies often push higher. Always confirm the exact figure with the builder in writing, because there is no statutory cap on loading; RERA only mandates that the carpet area be disclosed honestly.
A worked example
Say a builder advertises a 1,000 sq ft flat at ₹8,000 per sq ft on super built-up area — a ₹80 lakh apartment.
| Scenario | Loading | Carpet area | Effective price/sq ft on carpet | | A | 20% | ~833 sq ft | ~₹9,600 | | B | 30% | ~769 sq ft | ~₹10,400 | | C | 40% | ~714 sq ft | ~₹11,200 |
The flat costs the same ₹80 lakh, but the *real* rate for the space you use jumps from ₹9,600 to ₹11,200 as loading rises. Two projects quoting "₹8,000/sq ft" can be very different deals once you normalise on carpet area. When you compare listings on UrbanYardz property search, recalculate every shortlisted flat on carpet area so you are comparing apples to apples.
How to Verify Carpet Area Before You Pay
Do not take the brochure's word for it. Run this checklist:
1. Read the sale agreement. It must state the RERA carpet area. If it only mentions super built-up, demand the carpet figure in writing. 2. Cross-check the state RERA portal. The registered project page lists declared area details. 3. Get the architect's floor plan and confirm the internal dimensions match the stated carpet area. 4. Measure the ready flat yourself. For a ready-to-move or near-complete unit, a tape measure (or a laser measure) wall-to-wall gives you the real carpet area. Tolerance of a percent or two is normal; large gaps are a red flag. 5. Ask for the loading factor explicitly. A confident, RERA-compliant builder will state it without hesitation.
Carpet, Built-Up and Your Other Costs
The area definition ripples into several other numbers:
- Stamp duty and registration: These are charged on the agreement value or the state's ready-reckoner/circle rate, whichever is higher. Stamp duty rates vary widely by state — commonly in the 4–8% band as of 2026, with concessions for women buyers in several states. Confirm the current rate with your sub-registrar or your lawyer.
- Maintenance charges: Often levied per sq ft on super built-up area, so a high loading means higher monthly maintenance too — not just a higher purchase price.
- Property tax: Municipal bodies use their own area and valuation basis; check your local corporation's rule.
None of these change the core lesson: the usable space is the carpet area, and every other cost should be evaluated against it.
A Quick Buyer's Rule of Thumb
When you see a listing, mentally convert it:
- Carpet area = what you live in. This is the honest number.
- Built-up ≈ carpet + ~10–15%.
- Super built-up ≈ carpet + 25–40% (the loading).
If a listing only advertises super built-up, treat the real flat as roughly 70–80% of that figure until the builder confirms otherwise. Browse verified listings with clear area disclosures on UrbanYardz and always anchor your decision to carpet area.
Frequently Asked Questions
What is the difference between carpet area and built-up area?
Carpet area is the net usable floor space inside your flat where you can literally lay a carpet, excluding external wall thickness. Built-up area adds the wall thickness and balconies on top of carpet area, typically making it 10–15% larger.
Is carpet area or super built-up area shown in RERA?
Under RERA 2016, builders must disclose and sell on carpet area, defined as the net usable internal floor area excluding external walls, shafts, balconies and common spaces. Super built-up area cannot be the legal basis of sale for a RERA-registered project.
What is a good loading factor in 2026?
Loading is the gap between super built-up and carpet area. A loading of roughly 20–30% is common in Indian cities as of 2026; above 40% usually means you are paying heavily for shared amenities. Always confirm the exact figure with the builder in writing.
How do I calculate carpet area from super built-up area?
Use: carpet area ≈ super built-up area ÷ (1 + loading factor). For example, a 1,000 sq ft super built-up flat at 30% loading gives roughly 769 sq ft of carpet area. Ask the builder for the exact RERA-declared carpet area.
Does the price per square foot use carpet or super built-up area?
Builders often quote price per sq ft on super built-up area to make the rate look lower. Recalculate the effective price on carpet area so you can compare projects on a true, like-for-like basis.
Where can I find the carpet area of a property before buying?
Check the RERA-registered sale agreement and the project page on your state RERA portal, both of which must state carpet area. Verify it against the architect's floor plan and a physical measurement before paying.
Buying smart starts with knowing what you actually pay for. Use UrbanYardz to compare homes on carpet area, spot inflated loading factors, and shortlist properties with transparent area disclosures — so the space in your brochure matches the space you live in.