How to use this calculator
- Enter or choose plot area.
- Enter or choose total built-up area (all floors).
- Enter or choose ground-floor footprint.
- Enter or choose permitted FAR / FSI.
- The built-up area ratio (FAR / FSI) updates as you type. Use Copy result or Share to keep it.
Method
FAR = Total built-up area ÷ Plot area; Ground coverage = Footprint ÷ Plot area × 100; Maximum built-up = Permitted FAR × Plot area; Floors ≈ Built-up ÷ Footprint
- Built-up area
- floor area of all storeys, measured as your local rules define it
- Footprint
- the ground area covered by the building
Worked example
- FAR = 6,000 ÷ 4,000 = 1.5.
- Ground coverage = 2,000 ÷ 4,000 = 50%.
- At a permitted FAR of 2, the maximum is 2 × 4,000 = 8,000, leaving 2,000 to build.
The building has a FAR of 1.5 and covers half the plot; another 2,000 units of floor area fit within a FAR of 2.
What the result means
A FAR of 1.5 means the floor area equals one and a half times the plot. If the result is over your permitted limit, the extra area may need approval or a purchased development right, depending on local rules.
Assumptions and limits
- All areas are in the same unit.
- The permitted FAR is the one you enter; what counts towards it (balconies, stairs, parking) depends on local rules.
- Does not apply setbacks, height limits or premium FSI schemes, which can restrict or extend what you can build.
Questions
Is FAR the same as FSI?
Yes. Floor area ratio and floor space index are two names for the same ratio. Some places write it as a percentage (FAR 1.5 = 150%).
What is the difference between carpet, built-up and super built-up area?
Carpet area is the usable floor inside the walls; built-up adds the walls and balconies; super built-up adds a share of common areas. FAR rules specify which areas count.
Please note: Quantities are estimates. Confirm requirements with your engineer or supplier before ordering materials.