FSI Calculator & Guide
Your comprehensive guide to understanding and calculating Floor Space Index (FSI) regulations across India.
FSI Calculator
Calculate the permissible built-up area for your plot based on FSI regulations
Understanding FSI/FAR
Floor Space Index (FSI) and Floor Area Ratio (FAR) are fundamental concepts in urban planning that determine how much you can build on a given plot of land.
FSI (Floor Space Index) is the ratio of the total built-up area on all floors to the total plot area. It determines the maximum construction area allowed on a property.
FSI = Total Built-up Area ÷ Plot Area
Example: If FSI = 1.5 and plot area = 1000 sq.m, then maximum built-up area = 1500 sq.m
FAR (Floor Area Ratio) is synonymous with FSI. Some regions use FAR terminology, often expressing it as a percentage (e.g., FAR 150% = FSI 1.5).
Types of FSI
The standard FSI allowance provided by local development authorities without any additional cost.
Example:
Ahmedabad residential base FSI: 1.2-1.8 depending on road width and zone
Additional FSI that can be purchased from the development authority by paying a premium fee.
Example:
In Ahmedabad, residential properties can purchase premium FSI up to 2.7 total
Development rights that can be transferred from one plot to another, often used for road widening compensation.
Example:
If land is acquired for public use, owner receives TDR to use on another property
Factors Affecting FSI
Each city has unique FSI regulations based on:
- Urban density targets
- Infrastructure capacity
- Development plan zones
- Local building codes
FSI varies by property use:
- Residential: Generally lower FSI (1.2-2.0)
- Commercial: Higher FSI (1.8-4.0)
- Mixed-use: Combination of both
- Industrial: Specific regulations apply
Wider roads allow higher FSI:
- Less than 9m: Lower FSI
- 9-12m: Moderate FSI
- 12-18m: Higher FSI
- 18m+: Maximum FSI
Other considerations:
- Larger plots may have different rules
- Corner plots often get FSI benefits
- Special zones (TOD, CBD) have higher FSI
- Heritage zones may have restrictions
FSI Calculation Examples
Calculation:
Permissible Built-up Area = 1000 × 1.8 = 1,800 sq.m
This means you can construct up to 1,800 sq.m across all floors (e.g., 6 floors of 300 sq.m each).
Calculation:
Permissible Built-up Area = 500 × 4.0 = 2,000 sq.m
Wide roads in Mumbai allow significantly higher FSI, enabling vertical development.
Calculation:
Permissible Built-up Area = 250 × 1.2 = 300 sq.m
Narrow roads result in lower FSI to maintain adequate light, ventilation, and access.
For Property Buyers
- Understand development potential of a plot
- Evaluate if builder is utilizing full FSI
- Compare value across different properties
- Plan future expansion possibilities
For Developers
- Calculate maximum buildable area
- Determine project feasibility and ROI
- Plan unit mix and floor layouts
- Optimize land acquisition decisions
For Urban Planning
- Control urban density and sprawl
- Ensure adequate infrastructure capacity
- Balance development with livability
- Promote sustainable urban growth
For Investment Decisions
- Assess true value of land parcels
- Identify high-potential locations
- Understand regulatory constraints
- Make informed purchase decisions
Understanding FSI is crucial for anyone involved in real estate—whether buying, selling, developing, or investing. It directly impacts property value, development potential, and investment returns.
City-Wise FSI Information
Explore FSI regulations across major Indian cities. Each city has unique rules based on local development plans and infrastructure.
Base FSI
1.2 (residential), 1.8 (commercial)
Maximum FSI (with Premium)
2.7 (residential), 4.0 (commercial)
Road Width Impact
9m+ roads allow 1.5 FSI, 12m+ allow 1.8 FSI, 18m+ allow 2.0 FSI
Special Zones
Transit-Oriented Development (TOD) zones along BRTS/Metro corridors allow up to 4.0 FSI; Ashram Road CBD allows up to 5.4 FAR
TDR/Premium FSI
Yes, purchasable premium FSI and TDR available
Official Sources
Base FSI
1.33 (both residential and commercial)
Maximum FSI (with Premium)
5.0 (with premium FSI and TDR)
Road Width Impact
9m+ roads allow 1.5 FSI, 12m+ allow 2.0 FSI, 30m+ allow 3.0-4.0 FSI
Special Zones
Island City has lower base FSI; Suburbs have higher allowances; Special zones near transit hubs
TDR/Premium FSI
Yes, extensive TDR market and premium FSI options
Official Sources
Base FSI
1.2 (residential), 1.5 (commercial)
Maximum FSI (with Premium)
2.0 (residential), 3.0 (commercial)
Road Width Impact
12m+ roads allow 1.5 FSI, 24m+ allow 2.0-3.0 FSI
Special Zones
Different zones (residential, commercial, mixed-use) have varying FSI limits
TDR/Premium FSI
Limited TDR availability; Premium FSI in select areas
Official Sources
Base FSI
1.0 (residential), 1.2 (commercial)
Maximum FSI (with Premium)
4.0 (with premium FSI)
Road Width Impact
9m+ roads allow 1.2 FSI, 12m+ allow 1.5 FSI
Special Zones
Core city areas have lower FSI; Peripheral areas allow higher FSI
TDR/Premium FSI
Yes, TDR and premium FSI available
Official Sources
Base FSI
1.75 (residential), 2.5 (commercial)
Maximum FSI (with Premium)
4.0 (with premium FSI)
Road Width Impact
12m+ roads allow 2.5 FSI, 18m+ allow 3.25-4.0 FSI
Special Zones
IT corridors and special economic zones have higher FSI allowances
TDR/Premium FSI
Yes, TDR and additional FSI purchasable
Official Sources
Transit-Oriented Development (TOD) Zones
Properties within 200 meters of BRTS and Metro stations can avail FSI up to 4.0, promoting high-density development near public transport.
Central Business District (CBD) - Ashram Road
The Ashram Road CBD area allows special FAR up to 5.4 for tall buildings, making it one of the highest FSI zones in Ahmedabad.
Development Plan Zones
Different zones in Ahmedabad's development plan have varying FSI allocations based on infrastructure capacity, land use, and urban planning objectives.
What is the difference between FSI and FAR?
FSI (Floor Space Index) and FAR (Floor Area Ratio) are essentially the same concept with different names. FSI is commonly used in India, while FAR is the term used internationally. Both represent the ratio of total built-up area to plot area. For example, an FSI of 1.5 means you can build 1.5 times your plot area across all floors.
Can I exceed the allowed FSI for my property?
Yes, in most cities you can exceed the base FSI by purchasing Premium FSI or utilizing Transferable Development Rights (TDR). The maximum FSI varies by city - for example, Ahmedabad allows up to 2.7 FSI for residential properties with premium FSI, while Mumbai allows up to 5.0 FSI in certain areas. However, this comes at an additional cost and must comply with local regulations.
How is FSI calculated for basement and parking areas?
Generally, basement areas used exclusively for parking, utilities, or storage are not counted in FSI calculations in most Indian cities. However, if the basement is used for commercial purposes or habitable spaces, it may be included in the FSI calculation. Ground floor parking areas are typically exempt from FSI calculations, but this varies by city and specific regulations. Always verify with your local development authority for precise rules.
Does road width affect the FSI I can get?
Yes, road width is a crucial factor in determining FSI. Properties on wider roads typically qualify for higher FSI. For example, in Ahmedabad, residential properties on roads less than 9 meters wide get base FSI of 1.2, while those on roads 18 meters or wider can get FSI of 2.0 or more. This is because wider roads can handle higher traffic and population density.
What are special FSI zones?
Special FSI zones are designated areas where higher FSI is permitted to encourage development. Examples include Transit-Oriented Development (TOD) zones near metro stations and BRTS corridors in Ahmedabad (FSI up to 4.0), Central Business Districts (CBD) like Ashram Road in Ahmedabad (FSI up to 5.4), and IT/SEZ zones in cities like Bangalore and Pune. These zones aim to promote vertical development and efficient land use.
How do I calculate the number of floors I can build?
The number of floors depends on your FSI and the floor plate area. Formula: Number of floors = (Plot Area × FSI) ÷ Floor Plate Area. For example, with a 1000 sqm plot, FSI of 1.8, and floor plate of 600 sqm: (1000 × 1.8) ÷ 600 = 3 floors. However, you must also comply with height restrictions, setback requirements, and other building regulations that may limit the number of floors regardless of FSI.