FSI stands for Floor Space Index. It represents the ratio of the total built-up floor area across all levels of a building to the total area of the plot it stands on.

FAR stands for Floor Area Ratio. It is mathematically identical to FSI, but is sometimes expressed as a percentage instead of a decimal. For example, an FSI of 2.0 corresponds to a FAR of 200%.

What is the difference between FAR and FSI?

There is no mathematical difference. FSI is widely used in cities like Mumbai, Chennai, and Bengaluru as a decimal ratio (e.g., 2.5), whereas FAR is used in Delhi and northern regions as a percentage (e.g., 250%).

How is FSI calculated?

FSI is calculated using the formula: FSI = Total Built-up Area / Plot Area. For instance, a 1,000 sq ft building on a 1,000 sq ft plot has an FSI of 1.0.

How is FAR calculated?

FAR is calculated using the formula: FAR = (Total Floor Area / Plot Area) × 100. A 2,000 sq ft building on a 1,000 sq ft plot has a FAR of 200%.

How do I calculate permissible built-up area?

Permissible Built-up Area = Plot Area × Permissible FSI. If your plot is 3,000 sq ft and the FSI is 1.5, you can construct a maximum of 4,500 sq ft gross floor area.

How much can I build on a 1,000 sq ft plot?

It depends on the permissible local FSI. If the FSI is 2.0, you can build up to 2,000 sq ft total floor area, distributed across multiple floors depending on ground coverage and setbacks.

Does FSI include all floor areas?

No. Most municipal bylaws exclude specific areas from FSI calculations, such as basements used for parking, open balconies, lift shafts, staircases, and fire escape pathways.

What is the relationship between FSI and ground coverage?

Ground coverage limits the footprint of the ground floor, while FSI controls the total building volume. For example, on a 2,000 sq ft plot with 50% coverage and FSI 2.0, the ground footprint cannot exceed 1,000 sq ft, and you can build 4 floors of 1,000 sq ft each to reach the 4,000 sq ft limit.

Does higher FSI mean more floors?

Yes, usually. A higher FSI allows you to build more total space, which requires stacking more floors if your ground coverage is limited by setbacks.

Does FSI determine building height?

FSI limits total volume, but building height is also governed by other bylaws, such as the width of the fronting road, set back margins, and airport boundary restrictions.

Does road width affect permissible development?

Yes. Most cities correlate permissible FSI with road width to prevent traffic congestion. Wider roads are generally allowed higher FSI (often through premium purchased FSI).

Does FSI vary by location?

Yes, FSI varies significantly across cities, states, and zones. Core commercial zones have much higher FSI compared to residential suburbs or heritage zones.

Does residential FSI differ from commercial FSI?

Yes. Commercial buildings typically receive higher FSI allocations because they accommodate higher business densities, though they also require greater parking clearances.

FAR / FSI Calculator – Floor Area Ratio & Permissible Built-up

FAR / FSI Calculator

Calculate Floor Area Ratio (FAR) and Floor Space Index (FSI), permissible built-up area, ground coverage, setbacks, and building potential. Localized presets for Mumbai, Delhi, and Bengaluru.

⚡ Interactive Calculation Engine Active

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How to Use FAR / FSI Calculator

Choose calculation mode: Forward (Max Built-up) or Reverse (Required Plot, actual FSI, coverage).
Select plot units (sq ft, sq m, bigha, cents, guntha, etc.) and enter plot details.
Input permissible FSI/FAR ratio and ground coverage limit.
Optionally toggle Professional Mode to add setbacks (front, rear, side) and road width constraints.
Add floor-wise details in the Floor Area Planner to audit your utilization percentage.
Compare up to 3 building layouts side-by-side or download your planning report as a PDF.

What is Floor Area Ratio (FAR) & Floor Space Index (FSI)?

Floor Area Ratio (FAR) and Floor Space Index (FSI) are town planning density limits that determine the maximum buildable floor area allowed on a piece of land. Mathematically, FSI is a decimal ratio (e.g., 1.5, 2.5) while FAR is represented as a percentage (e.g., 150%, 250%). For example, an FSI of 2.0 (or 200% FAR) on a 2,000 sq ft plot allows you to construct a maximum of 4,000 sq ft of total built-up area across all floor levels combined.

FSI & FAR Formula

The mathematical equations governing FSI are simple and direct: • Floor Space Index (FSI) = Total Built-up Area / Plot Area • Floor Area Ratio (FAR) = (Total Built-up Area / Plot Area) × 100 • Permissible Built-up Area = Plot Area × Permissible FSI • Required Plot Area = Desired Floor Area / Permissible FSI

FSI and Ground Coverage Relationship

Ground coverage restricts the horizontal footprint of the building on the soil, while FSI controls the vertical volume. For instance, on a 5,000 sq ft plot with 40% ground coverage (2,000 sq ft maximum footprint) and an FSI of 2.0 (10,000 sq ft total permissible area), the ground floor footprint cannot exceed 2,000 sq ft. To fully utilize the 10,000 sq ft construction potential, you would stack five identical floor levels of 2,000 sq ft each.

Step-by-Step FSI Area Calculation Example

Let's calculate the permissible building potential for a typical residential plot in India: 1. Plot Dimensions: 40 ft width by 60 ft depth = 2,400 sq ft plot area. 2. Permissible FSI: 1.75 (from local municipal bye-laws). 3. Maximum Ground Coverage: 50% (allows a 1,200 sq ft footprint). 4. Total Permissible Built-up Area = 2,400 sq ft × 1.75 = 4,200 sq ft. 5. Floor Plan Strategy: - Ground Floor: 1,200 sq ft (utilizing full coverage) - First Floor: 1,200 sq ft - Second Floor: 1,200 sq ft - Third Floor: 600 sq ft (remaining FSI capacity) - Total Built-up: 4,200 sq ft (Exactly utilizing FSI limit)

FSI Exclusions: What is Exempted from FSI?

Not all constructed spaces count toward your permissible FSI. Under most Indian municipal rules (like MCGM DCPR 2034 or BBMP bye-laws), the following areas are usually 'Free of FSI' (excluded): • Basement areas used exclusively for car parking or installation of machinery/utilities. • Open-to-sky balconies, terraces, and ventilation shafts. • Staircase cabins, lift shafts, and common lift lobbies. • Stilt parking floors left open to the elements. • Fire escape staircases and refuge areas.

Gross Plot Area vs. Net Plot Area (Road Widening)

FSI calculations are always based on the Net Plot Area, not the gross land area. If a portion of your plot is zoned for municipal road widening, public amenity reservations, or green belt setback dedication, that area must be deducted first. Permissible built-up area is then calculated using the remaining net plot size, though some authorities offer Compensatory FSI or Transferable Development Rights (TDR) for the surrendered land.

Frequently Asked Questions

What is FSI?: FSI stands for Floor Space Index. It represents the ratio of the total built-up floor area across all levels of a building to the total area of the plot it stands on.
What is FAR?: FAR stands for Floor Area Ratio. It is mathematically identical to FSI, but is sometimes expressed as a percentage instead of a decimal. For example, an FSI of 2.0 corresponds to a FAR of 200%.
What is the difference between FAR and FSI?: There is no mathematical difference. FSI is widely used in cities like Mumbai, Chennai, and Bengaluru as a decimal ratio (e.g., 2.5), whereas FAR is used in Delhi and northern regions as a percentage (e.g., 250%).
How is FSI calculated?: FSI is calculated using the formula: FSI = Total Built-up Area / Plot Area. For instance, a 1,000 sq ft building on a 1,000 sq ft plot has an FSI of 1.0.
How is FAR calculated?: FAR is calculated using the formula: FAR = (Total Floor Area / Plot Area) × 100. A 2,000 sq ft building on a 1,000 sq ft plot has a FAR of 200%.
How do I calculate permissible built-up area?: Permissible Built-up Area = Plot Area × Permissible FSI. If your plot is 3,000 sq ft and the FSI is 1.5, you can construct a maximum of 4,500 sq ft gross floor area.
How much can I build on a 1,000 sq ft plot?: It depends on the permissible local FSI. If the FSI is 2.0, you can build up to 2,000 sq ft total floor area, distributed across multiple floors depending on ground coverage and setbacks.
Does FSI include all floor areas?: No. Most municipal bylaws exclude specific areas from FSI calculations, such as basements used for parking, open balconies, lift shafts, staircases, and fire escape pathways.
What is the relationship between FSI and ground coverage?: Ground coverage limits the footprint of the ground floor, while FSI controls the total building volume. For example, on a 2,000 sq ft plot with 50% coverage and FSI 2.0, the ground footprint cannot exceed 1,000 sq ft, and you can build 4 floors of 1,000 sq ft each to reach the 4,000 sq ft limit.
Does higher FSI mean more floors?: Yes, usually. A higher FSI allows you to build more total space, which requires stacking more floors if your ground coverage is limited by setbacks.
Does FSI determine building height?: FSI limits total volume, but building height is also governed by other bylaws, such as the width of the fronting road, set back margins, and airport boundary restrictions.
Does road width affect permissible development?: Yes. Most cities correlate permissible FSI with road width to prevent traffic congestion. Wider roads are generally allowed higher FSI (often through premium purchased FSI).
Does FSI vary by location?: Yes, FSI varies significantly across cities, states, and zones. Core commercial zones have much higher FSI compared to residential suburbs or heritage zones.
Does residential FSI differ from commercial FSI?: Yes. Commercial buildings typically receive higher FSI allocations because they accommodate higher business densities, though they also require greater parking clearances.