About This Calculator
This calculator helps you determine the Floor Space Index (FSI), also known as Floor Area Ratio (FAR), based on plot area and built-up area. It also allows reverse calculation to estimate the permissible built-up area from a known FSI. Units are selectable (m², ft², acres), and all results are shown using the same unit as the plot area.
How It Works
- Select the calculation mode:
- Built-up Area to FSI: Enter plot and built-up areas to calculate FSI.
- FSI to Built-up Area: Enter plot area and FSI to calculate total buildable area.
- Choose your preferred area unit for each input: square meters (m²), square feet (ft²), or acres.
- If the input units are different, the calculator will automatically convert them using the plot area’s unit as the reference.
- Click "Calculate" to see the result.
Frequently Asked Questions
What is Floor Space Index (FSI)?
FSI is the ratio of total built-up floor area to the area of the plot. It is a key measure of building density in urban planning.
What units can I use?
The calculator supports square meters (m²), square feet (ft²), and acres. You can select the unit for each input field.
What if I input different units?
The calculator will automatically convert all values to match the plot area’s unit before calculation. The result will also use that same unit.
Can FSI have units?
No. FSI is a ratio and has no unit—it simply represents how much floor space is allowed relative to plot area.
Is this calculator suitable for building regulations?
Yes. It helps quickly estimate buildable limits or verify existing area ratios in real estate, architecture, or zoning review.