Floor Area Ratio (FAR/FSI) Calculator

Compare total floor area with plot area to calculate FAR or FSI. Enter your own values below to see floor area ratio / FSI and check the method behind it.

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Your result

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Fill in your inputs and select Calculate.
Your result and breakdown will appear here.

How this calculator works

FAR = counted total floor area across floors ÷ plot area. Local exclusions must be applied to the entered floor area.

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What is Floor Area Ratio (FAR/FSI) Calculator?

Floor Area Ratio (FAR/FSI) Calculator helps you compare total floor area with plot area to calculate FAR or FSI.

The main result is floor area ratio / FSI. The formula, example and assumptions below explain how to interpret it.

How to use Floor Area Ratio (FAR/FSI) Calculator

Use the example to get familiar with the form, then enter your own figures. Any rates in the example are illustrative. Check the field labels and units before calculating.

  1. Gather total floor area counted by local rules (m²) and plot area (m²). Use values from the same situation or reporting period.
  2. Replace the example total floor area counted by local rules with your own value, then complete the other fields. Check the displayed units.
  3. Select Calculate and read floor area ratio / FSI. Change one input and calculate again to compare a second scenario. Reset restores the original example.
  • Enter total floor area counted by local rules in m², at least 0. Decimals are accepted.
  • Enter plot area in m², at least 0.001. Decimals are accepted.

Floor Area Ratio (FAR/FSI) Calculator: a worked example

With the inputs below, the result is 2.5 × (floor area ratio / FSI). Follow the example, then replace these illustrative values with your own.

Example inputs and output
Input or outputExample value
Total floor area counted by local rules (m²)5,000 m²
Plot area (m²)2,000 m²
Floor area ratio / FSI2.5 ×

Understanding the Floor Area Ratio (FAR/FSI) result

The main output is floor area ratio / FSI, expressed in ×. It applies to the inputs and operation you selected.

Displayed results use a readable number of decimal places. When checking a result by hand, keep extra precision until the last step. To compare scenarios, change one input at a time and keep the others fixed.

Floor Area Ratio (FAR/FSI) Calculator: assumptions and common mistakes

A useful estimate starts with the right inputs. Check the following assumptions and limits before applying the result to your situation.

  • Keep dimensions in the displayed units and distinguish usable area from built-up area. Material estimates need a suitable allowance for site conditions and waste.

For wider guidance, visit Bureau of Indian Standards. The formula and scope of this specific tool are stated on this page.

Floor Area Ratio (FAR/FSI) Calculator FAQs

What does Floor Area Ratio (FAR/FSI) Calculator calculate?

Floor Area Ratio (FAR/FSI) Calculator helps you compare total floor area with plot area to calculate FAR or FSI. Its main output is floor area ratio / FSI in ×.

What inputs do I need for Floor Area Ratio (FAR/FSI) Calculator?

You need total floor area counted by local rules (m²) and plot area (m²). Use the field labels and units to match your figures to the formula.

Which formula does Floor Area Ratio (FAR/FSI) Calculator use?

FAR = counted total floor area across floors ÷ plot area. Local exclusions must be applied to the entered floor area.

What is a worked example for Floor Area Ratio (FAR/FSI) Calculator?

Example inputs: Total floor area counted by local rules: 5,000 m²; Plot area: 2,000 m². The result is 2.5 × (floor area ratio / FSI).

How should I enter total floor area counted by local rules?

Enter total floor area counted by local rules in m², at least 0. Decimals are accepted.

How do I choose plot area?

Enter plot area in m², at least 0.001. Decimals are accepted. The example uses 2,000 m²; replace it if your circumstances differ.

How should I read floor area ratio / FSI?

The main output is floor area ratio / FSI, expressed in ×. It applies to the inputs and operation you selected.

Why might my Floor Area Ratio (FAR/FSI) Calculator result differ from my records?

Keep dimensions in the displayed units and distinguish usable area from built-up area. Material estimates need a suitable allowance for site conditions and waste. Differences in entered values, units or rounding can also change the comparison.

Can I compare two scenarios in Floor Area Ratio (FAR/FSI) Calculator?

Yes. Note your first floor area ratio / FSI, change total floor area counted by local rules or another input, and select Calculate again. Editing a field clears the old result so it is not mistaken for a new calculation.

Is Floor Area Ratio (FAR/FSI) Calculator free, and where are my inputs calculated?

This calculator is free to use without signing in. Its formula runs in your browser; calculator inputs are not sent to a calculation API. The inputs reset to the example values when you reset the form or start a fresh page.