Convert carpet ↔ built-up ↔ super built-up
Default: 1400 sqft super built-up with 70% carpet / 87% built-up efficiency (typical tier-1 project).
The three Indian area types, defined
Carpet area is the net usable floor space inside the apartment — what you could carpet. It excludes walls, balconies, and common areas. RERA (Section 2(k)) defines it as “net usable floor area excluding external walls.” All RERA-registered pricing is legally per carpet sqft.
Built-up area = carpet area + wall thickness + balcony + utility area. Typically 10–20% larger than carpet. This is what most older builders quoted before RERA.
Super built-up area = built-up + proportionate share of common areas (lobbies, lifts, club, corridors). Typically 15–30% larger than built-up. This is what broker brochures and pricing websites use, because the larger number lets them quote a lower per-sqft rate.
Typical Indian efficiency ratios: carpet ÷ super built-up = 65–75% (median 70%). Built-up ÷ super built-up = 85–90%. Check the builder’s RERA approval document for the exact ratios of your specific project — it’s a legal requirement.
How a 2 BHK “1400 sqft” listing breaks down
| Listed as | Efficiency | Carpet area | Real cost per carpet sqft |
|---|---|---|---|
| 1400 sqft super (at ₹8,000/sqft) | 70% | 980 sqft | ₹11,429/sqft |
| 1400 sqft super (at ₹8,000/sqft) | 75% | 1050 sqft | ₹10,667/sqft |
| 1400 sqft built-up (at ₹8,000/sqft) | 87%/70% | 1126 sqft | ₹9,947/sqft |
| 1400 sqft carpet (at ₹8,000/sqft) | — | 1400 sqft | ₹8,000/sqft |
Same headline price and area, four very different real costs per usable square foot. Always ask the builder for the RERA carpet-area number before comparing across projects.
Frequently asked
Which area is mandatory under RERA in India?
Carpet area. Since RERA came into force in 2017, every builder of a RERA-registered project must declare and price per carpet area — not super built-up. This is legally binding on all advertising, sale agreements, and payment schedules. Quoting super built-up pricing in a sale contract is a RERA violation.
What is a “good” carpet efficiency percentage?
In Indian tier-1 cities, carpet efficiency (carpet ÷ super built-up) ranges 65–75%. Above 72% is efficient — typically in well-designed projects with minimal wasted lobby space. Below 65% is inefficient — usually in luxury projects with large lobbies, double-height clubhouses, and long corridors, or in projects where the builder inflated super built-up to understate headline pricing.
Can a builder change the carpet area after booking?
Only by up to ±3% under RERA. If the actual carpet area at handover differs by more than 3% from the agreement value, the buyer is entitled to a pro-rata price refund for the shortfall. If more than 5%, the buyer can opt to cancel the booking with full refund plus interest. Check the Sale Agreement for the declared carpet area before signing.
Why do brokers still quote super built-up area?
Two reasons: (a) marketing — the number is 25–40% larger than carpet, so the per-sqft rate looks smaller; (b) legacy — pre-RERA (before 2017) super built-up was standard. Any legitimate RERA-approved project must also publish carpet area in its sale agreement and on the state RERA portal. If a broker refuses to share the carpet figure, treat it as a red flag.
Is balcony included in carpet area?
No. RERA specifically excludes balcony, open terrace, verandah, and utility area from carpet area. These are typically 50–80 sqft for a 2 BHK. They’re usable but do not count toward the RERA-mandated carpet number. The sale agreement lists them as separate line items (usually at 50% weighting in price).