Carpet Area Calculator
This carpet area calculator converts the super built-up area (or carpet area) quoted in your builder's brochure into the actual usable floor space you'll get. Enter your numbers below to instantly see carpet area, RERA loading factor, efficiency %, true price per carpet sq ft, and a KnowAndInvest verdict on whether the loading is fair.
Free, RERA-aligned, and updates live as you type — no signup required.
If you don't know carpet area, pick a loading factor typical for your segment. The calculator will estimate carpet area from SBA.
Under RERA, balcony is included in carpet area. Older sale deeds may exclude it.
How Does Your Apartment Compare?
Typical efficiency ranges by apartment segment in India. Your apartment is highlighted.
| Segment | Loading Factor | Efficiency Range | Typical SBA | Rating |
|---|---|---|---|---|
| Luxury / Villa plots Independent villa, plotted dev. | 1.05–1.15× | 87–95% | Low relevance | ✦ Excellent |
| Premium Apartments High-rise, branded developers | 1.15–1.25× | 80–87% | 1,500–4,000 sq ft | ✦ Excellent |
| Mid-Segment Apartments Most private developers | 1.25–1.35× | 74–80% | 800–1,800 sq ft | ✓ Good |
| Your Apartment Loading 1.39× → 72% | 1.39× | 72% | 1,200 sq ft | ✓ Good |
| Budget / Affordable Govt schemes, budget dev. | 1.35–1.45× | 69–74% | 400–900 sq ft | ~ Average |
| Old Construction / MHADA Pre-2000, redevelopment | 1.45–1.65× | 61–69% | Varies widely | ✗ Poor |
Super Built-Up, Built-Up & Carpet Area Explained
Every area term in Indian real estate has a precise meaning — and they are often used interchangeably by builders in ways that obscure the true picture.
The net usable floor area inside your apartment — what you can literally lay a carpet on. Under RERA 2016, this is the mandatory disclosure unit for all new residential projects.
Includes: Living room, bedrooms, kitchen, bathrooms, internal corridors, balconies (RERA definition).
Excludes: Thickness of walls, common areas, lobby, staircase, lift shaft.
Carpet area + the area covered by walls (typically 10–15% of carpet). This is the footprint of your individual unit including its structural envelope.
Formula: Built-Up ≈ Carpet × 1.10 to 1.15. The difference (walls) is typically 120–180 sq ft for a 1,000 sq ft carpet area apartment.
Built-up area + your proportionate share of common areas: lobby, corridors, lift shaft, staircase, clubhouse, pump room, security room, etc.
This is what builders historically quoted prices on. It is always the largest of the three and makes the per-sq-ft price appear lower than it really is.
Loading factor = Super Built-Up ÷ Carpet Area. A loading factor of 1.30 means 30% of the SBA you're paying for is not your personal carpet space.
Acceptable range: 1.15×–1.30× for well-designed projects. Above 1.40× indicates either excessive common areas or an inflated SBA figure — both red flags.
Carpet Area Calculator — Formulas Used
- Carpet Area = Super Built-Up Area ÷ Loading Factor
- Loading Factor = Super Built-Up Area ÷ Carpet Area
- Carpet Area Efficiency (%) = (Carpet Area ÷ Super Built-Up Area) × 100
- Built-Up Area ≈ Carpet Area ÷ 0.88 (walls are typically ~12% of built-up area)
- True Price per Carpet Sq Ft = Total Apartment Price ÷ Carpet Area
