How to Calculate FSI for Redevelopment

FSI is one of the most important concepts in real estate redevelopment, yet it is also one of the most confusing.
Many property owners and societies are unclear about how redevelopment FSI works and how it differs from normal FSI.

In simple language, FSI decides how much construction is allowed on a plot.
In redevelopment projects, additional benefits such as TDR, fungible FSI and incentive FSI are added, which increases the total buildable area.

This guide explains how to calculate FSI for redevelopment in a clear and practical way, without technical jargon.

What Is FSI (Floor Space Index)

FSI stands for Floor Space Index.
It defines the maximum construction area allowed on a plot of land.

The basic FSI formula is:

FSI = Total Built-up Area ÷ Plot Area

For example, if your plot area is 1000 sq ft and the allowed FSI is 1.0, then the maximum construction allowed is 1000 sq ft.

To understand how land rules work before redevelopment, you can also read this guide:
Step by Step Guide to Buying a Plot in Maharashtra.

Why FSI for Redevelopment Is Different

In redevelopment projects, the government allows extra construction to encourage rebuilding of old buildings.
This makes redevelopment financially viable for both societies and developers.

Redevelopment FSI is higher because it supports:

• Rehabilitation of existing occupants
• Safety upgrades in old structures
• Better urban planning

This is why redevelopment FSI is different from normal FSI and often creates confusion.
You can also understand the land vs structure concept here:
Difference Between Plot and Flat.

What Is FSI for Redevelopment

Redevelopment FSI is not a single number.
It is a combination of multiple FSI components added together.

The redevelopment FSI formula is:

Total Redevelopment FSI = Base FSI + TDR + Fungible FSI + Incentive FSI

Each component plays a crucial role in increasing the total permissible construction.

Components Used in Redevelopment FSI Calculation

Plot Area

Plot area is the total land area on which redevelopment is proposed.
All FSI calculations are based on the plot area.

Larger plots usually allow higher construction potential.

Base FSI

Base FSI is the standard FSI permitted by the local planning authority.
It depends on:

• Location of the property
• Road width
• Zoning regulations

This is the starting point of redevelopment FSI calculation.

TDR (Transfer of Development Rights)

TDR is additional development potential that can be purchased and used on the plot.

In redevelopment, TDR increases construction area without increasing plot size.
TDR usage depends on local development control rules.

Fungible FSI

Fungible FSI is extra construction area allowed by paying a premium to the authority.

It is commonly used for:

• Balconies
• Flower beds
• Additional covered areas

Incentive FSI

Incentive FSI is granted specifically for redevelopment of old buildings.

It is provided to:

• Encourage redevelopment
• Improve building safety
• Support existing occupants

Example: FSI Calculation for Redevelopment

Normal FSI Calculation

Plot area = 1000 sq ft
Base FSI = 1.0

Normal construction allowed:

1000 × 1.0 = 1000 sq ft

Redevelopment FSI Calculation

Assume the following redevelopment benefits:

• Base FSI = 1.0
• TDR = 0.8
• Fungible FSI = 0.3
• Incentive FSI = 0.4

Total redevelopment FSI:

1.0 + 0.8 + 0.3 + 0.4 = 2.5

Total buildable area:

1000 × 2.5 = 2500 sq ft

FSI Calculation Summary Table

Why FSI Is Crucial for Redevelopment

FSI directly affects the success of a redevelopment project.

• Total saleable area
• Free area given to existing members
• Project feasibility
• Developer profitability

Factors Affecting FSI in Redevelopment

FSI varies based on several factors:

• Property location
• Road width
• Local development rules
• Type of redevelopment
• Municipal approvals

FSI varies by location, property type and development plans.
Always consult local laws before finalising redevelopment.

FAQs

What is FSI in simple words

FSI tells you how much construction is allowed on a plot of land.

Why is redevelopment FSI higher

To encourage rebuilding of old buildings and improve safety.

Is TDR compulsory for redevelopment

No, but it is commonly used to increase development potential.

Does FSI change by location

Yes, FSI differs based on city, zoning and development rules.

Final Advice

Understanding FSI calculation is essential for successful redevelopment.
It helps societies, owners and developers make informed decisions.

Always verify FSI rules with professionals and local authorities before starting redevelopment.

For legally planned developments and land projects, you can also explore:
UrbanBrick Vista NA Plots Near Hinjewadi.