Carpet Area vs Built-Up vs Super Built-Up: How Builders Inflate the Price Per Sq Ft
Super built-up area can be 35–50% larger than carpet area — meaning a flat quoted at ₹5,500/sq ft might actually cost you ₹8,000+ per usable sq ft. Here is how to see through the numbers and compare projects honestly.
Typical loading factor
SBA over carpet area, mid-segment
Luxury project loading
extensive amenity area
RERA requirement
carpet area disclosure since 2017
Price inflation from SBA
vs true carpet area cost
You're comparing two apartments. One builder quotes ₹5,500 per sq ft for a "1,400 sq ft" flat. Another quotes ₹7,000 per sq ft for a "950 sq ft" flat. The first sounds cheaper. But what you're actually comparing are two different definitions of "square feet" — and this confusion costs Indian buyers lakhs every year.
Three Definitions, One Flat
Carpet Area
The actual usable floor area inside your apartment — the area where you can literally lay carpet. It excludes walls, balconies, utility areas, and all common spaces.
Since RERA 2016, all developers must mandatorily disclose carpet area and price on carpet area basis for RERA-registered projects. This is now the legally valid measurement.
Built-Up Area (BUA)
Carpet area + the area of the walls and columns within your flat, plus balconies and terraces attached to your unit. Typically 10–15% more than carpet area.
Super Built-Up Area (SBA)
Built-up area + your proportionate share of common areas: lift lobbies, staircases, club house, gym, security cabin, passages, generator room, etc. Also called "saleable area" or "plinth area."
This is the number builders historically quoted (and many still quote informally). SBA is typically 20–35% more than carpet area in mid-segment projects — and up to 45–50% more in luxury projects with extensive amenities.
The Loading Factor: Where the Inflation Hides
The ratio of super built-up to carpet area is called the loading factor or loading percentage.
- Low loading (good for buyer): 20–25%. Seen in older, simpler buildings with minimal common areas
- Medium loading: 25–35%. Typical for most 2020s residential projects
- High loading (bad for buyer): 35–50%. Common in luxury high-rises with clubhouses, sky lounges, and multiple lobbies
Example calculation:
Project A: ₹5,500/sq ft × 1,400 sq ft (SBA) = ₹77 lakh total If loading is 35%, carpet area = 1,400 / 1.35 = 1,037 sq ft Effective carpet rate = ₹77L / 1,037 sq ft = ₹7,425/sq ft on carpet
Project B: ₹7,000/sq ft × 950 sq ft (carpet, RERA basis) = ₹66.5 lakh total Effective carpet rate = ₹7,000/sq ft on carpet
Project B is cheaper per usable sq ft — but Project A looks cheaper in the brochure. This is the exact game played in most sales conversations.
Post-RERA: What Builders Must Disclose
For RERA-registered projects, the Allotment Letter must state the carpet area, and the price must be quoted on carpet area basis. Builders cannot increase the carpet area-based price after allotment.
However, many builders get around this by:
- Adding "amenity charges" separately (not part of the per-sq-ft price)
- Quoting super built-up in informal communication even while complying with RERA on paper
- Using "apartment area" which may or may not equal carpet area
How to Compare Projects Correctly
Step 1: Get the carpet area from the RERA portal (search by project name) — this is the verified, legally accurate number
Step 2: Calculate the all-in cost ÷ carpet area = true cost per usable sq ft
Step 3: Compare this across projects, not the per sq ft quoted in advertisements
Step 4: Ask the builder for the floor plan with dimensions. Measure the internal rooms yourself (or verify from plan) — check that carpet area matches what's shown.
The Balcony Question
Under RERA, balconies are included in carpet area (at 50% of actual area). However, some states exempt terraces or utility balconies. Always check what exactly is included in the carpet area figure — some builders include service balconies that add to the number but not to usable living space.
Common Red Flags
- Builder refuses to quote price on carpet area basis
- Allotment letter specifies SBA without carpet area breakdown
- Significant difference between plan dimensions and stated carpet area
- Club charges, amenity charges, maintenance not disclosed upfront (these effectively increase cost per usable sq ft)
Practical Summary
Always ask: "What is the carpet area of this flat as per RERA?" Get the answer in writing. Calculate your cost on carpet area basis. Verify on the RERA portal — most states let you search by project and see the registered carpet area for each unit. A 35% loading project quoted at ₹6,000/sq ft (SBA) costs you ₹8,100/sq ft on actual usable area. That gap is not a builder's profit margin — it's what you're paying for corridors, lift shafts, and the lobby downstairs.
Quick take
- A project with 35% loading and ₹6,000/sq ft SBA price actually costs ₹8,100/sq ft on the area you can actually live in
- RERA mandates carpet area disclosure — if a builder refuses to give this in writing, treat it as a red flag
- Balconies are included in RERA carpet area at 50% of their actual size — verify what's being counted
- Luxury high-rises with sky lounges and clubhouses often have 45–50% loading — you're partly buying common space
When a builder quotes price per sq ft, always ask which sq ft — because super built-up area can be 50% larger than the area you'll actually sleep, cook, and live in.
Propzee Verdict
Super built-up area can be 35–50% larger than carpet area — meaning a flat quoted at ₹5,500/sq ft might actually cost you ₹8,000+ per usable sq ft. Here is how to see through the numbers and compare projects honestly.
