Carpet Area Formula

Real Estate Formula • Published on September 01, 2026 • Last updated September 01, 2026

Mathematical Equation

$$\text{Carpet Area} = \text{Super Built-Up Area} \times \left(1 - \frac{\text{Common Area}\%}{100}\right) \times \left(1 - \frac{\text{Wall}\%}{100}\right)$$

Variable Definitions

Super Built-Up Area

The saleable area quoted by developers, including proportionate common areas

Common Area %

Share of the super built-up area allocated to shared amenities like lobby, elevator, and parking (typically 10-45%)

Wall %

Share of the built-up area occupied by walls and balconies (typically 5-20%)

Detailed Explanation

In-Depth Guide

Key Concept

Carpet Area, Built-Up Area, and Super Built-Up Area are the three RERA-defined area measures used across Indian real estate listings.

Carpet Area is the actual usable floor space within the walls of a unit, while Super Built-Up Area — the figure most often quoted in pricing — adds walls, balconies, and a proportionate share of shared building amenities.

This formula lets a buyer work backward from the quoted saleable area to the real usable space.

How to Calculate: Step-by-Step

1. Start with the quoted Super Built-Up Area. 2. Subtract the Common Area% to remove the shared-amenity allocation, arriving at Built-Up Area. 3. Subtract the Wall% from the Built-Up Area to remove wall and balcony thickness. 4. The remaining figure is the Carpet Area — the actual usable floor space.

Worked Calculation Example

Super Built-Up Area = 1,500 sq ft, Common Area = 20%, Wall & Balcony Share = 10%: - Built-Up Area = 1,500 × (1 − 0.20) = 1,200 sq ft - Carpet Area = 1,200 × (1 − 0.10) = 1,080 sq ft - So of the 1,500 sq ft quoted, only 1,080 sq ft (72%) is actual usable floor space.

Common Use Cases

Verifying how much real usable space you get for a quoted saleable area price
Comparing the efficiency (carpet-to-super-built-up ratio) of different apartment projects
Cross-checking RERA-mandated carpet area disclosures on sale agreements

Frequently Asked Questions

Super Built-Up Area includes a share of common amenities that all residents use, so builders use it to fairly distribute the cost of shared spaces like lobbies and elevators across all units — though it makes per-sq-ft comparisons harder for buyers.

Yes, under India's Real Estate (Regulation and Development) Act, developers are legally required to quote and sell based on Carpet Area in the agreement, even if marketing materials reference Super Built-Up Area.

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