FAR & FSI Calculator
Enter your plot and the FAR or FSI figure from your local development rules. This FAR calculator multiplies them into the most floor area that counts toward the ratio, works out the ratio your own floors reach, or finds the plot a floor area needs.
FAR & FSI calculator
Planning aid, not a compliance check; FAR/FSI, coverage and setbacks are set by your local development rules. Not checked: height limits, exemptions, premium or purchasable FAR/TDR, road-width rules, parking and open-space requirements.
Bare numbers are meters; 190 mm works too.
FAR 1.5 and FAR 150 are the same limit. Switching the form keeps the number in each box, so enter your figure again in this form.
Assumptions
Change any value to match your product or local rules.
Basis: Example only: replace it with the figure from your local development rules.
Leave blank to skip the floor count.
Basis: Example only: replace it with the figure from your local development rules.
- Total floor area (FAR area)
- 1,000.00 m²
- 10,763.9 sq ft
- FAR / FSI
- 2.00 (200%)
- Plot area
- 500.00 m²
- 5,382.0 sq ft
- Against your FAR figure
- The most the figure you entered gives this plot
- Floors at full coverage
- 3 full floors + 100.00 m²
At FAR 2.00 (200%), a plot of 500.00 m² (5,382.0 sq ft) gives at most 1,000.00 m² (10,763.9 sq ft) of floor area that counts toward FAR.
How this was calculated
- Maximum floor area = plot area × FAR (a percent FAR is divided by 100 first)
- FAR reached = sum of the floor areas that count ÷ plot area
- Plot needed = floor area ÷ FAR
- Largest footprint = plot area × coverage ÷ 100; full floors = maximum floor area ÷ footprint, rounded down, plus what is left
- Plot area = 20.00 m × 25.00 m = 500.00 m²
- FAR = as entered = 2.00 (200%)
- Maximum floor area = 500.00 m² × 2.00 (200%) = 1,000.00 m²
- Largest footprint = 500.00 m² × 60% = 300.00 m²
- Full floors = 1,000.00 m² ÷ 300.00 m² = 3 full floors + 100.00 m²
How it works
Enter the plot
Type its area, or its width and depth if it is a rectangle. Sizes work in meters or feet; switch units at the top.
Enter your FAR or FSI
Use the figure your development rules give for your plot, as a ratio (1.5) or a percent (150). The default is an example only.
Pick what to work out
The most floor area at that figure, the ratio your floors reach (mark which floors count), or the plot a floor area needs.
Add coverage for a floor count
Enter a ground coverage figure and the calculator divides the floor area by the largest footprint to show how many full floors that makes.
Worked example
A 500 m² plot with an FAR of 2.0: 500 × 2.0 = 1,000 m² of floor area that counts toward FAR, about 10,763.9 sq ft. With 60% ground coverage the footprint can be up to 500 × 60 ÷ 100 = 300 m², so the 1,000 m² makes 3 full floors of 300 m² plus 100 m².
The other way round: ground, first and second floors of 280 m² each plus a 60 m² terrace room add up to 900 m². Basement parking of 280 m² is marked as not counted. 900 ÷ 500 = FAR 1.80, or 180%.
In feet, a 30 × 40 ft plot is 1,200 sq ft. At FAR 1.75 it gives 1,200 × 1.75 = 2,100 sq ft (195.096384 m²).
FAR and FSI: one ratio, two names
Floor area ratio (FAR) and floor space index (FSI) are the same number: total floor area divided by plot area. Both names are used in India: FSI is common in some states, FAR in others, and many other places say FAR or plot ratio. Some authorities write it as a percent, so FAR 150 means 1.5 times the plot. Pick the form your rules use and the calculator shows the other one beside it.
What counts toward FAR
Authorities differ on which floor areas count. Before you trust a figure, ask yours about:
• Basements and stilt or podium parking • Balconies, verandahs and terraces, open or covered • Stair and lift cores, lobbies and service shafts • Rooms on the roof, such as a terrace room or water tank room • Wall thickness: whether floor area is measured to the outer wall faces
Mark each floor row as counted or not to match your rules. The calculator shows both lists so you can check them.
From FAR to number of floors
FAR caps the total floor area; coverage caps the footprint on the ground. Divide the first by the second and you get the number of full floors: 1,000 m² ÷ 300 m² is 3 full floors with 100 m² left for a smaller fourth floor. A smaller footprint gives more floors for the same floor area. Height limits can stop you first, and this calculator does not check them.
Built-up area and FAR area
The floor area in an FAR sum is what your rules count, which can leave out parking, some balconies and service areas. Built-up area in a flat sale usually includes the walls and balconies of one flat, and super built-up area adds a share of the common areas. The figures can differ, so check which one a number refers to. For a flat’s areas, use the super built-up area calculator.
Frequently asked questions
What is the difference between FAR and FSI?
In the maths, none: both are total floor area ÷ plot area. Both names are used in India, FSI in some states and FAR in others; many other places say FAR. What counts toward the floor area can differ between authorities.
How do I calculate FAR?
Add the floor areas that count under your rules and divide by the plot area. 900 m² of counted floors on a 500 m² plot gives 900 ÷ 500 = 1.80.
How many floors can I build with FAR 2?
It depends on the footprint. Floors = plot × FAR ÷ footprint. On a 500 m² plot with a 300 m² footprint, FAR 2 gives 1,000 ÷ 300: 3 full floors and 100 m² more. Height limits and other rules may set a lower number.
Do basements and parking count toward FAR?
That depends on your rules. Many authorities leave out some parking or basement area, but the details vary. Mark each floor as counted or not in the calculator to match yours.
Why is FAR sometimes written as 150 instead of 1.5?
Some rules state it as a percent of the plot area. FAR 150 means the floor area can be 150% of the plot, the same as a ratio of 1.5. Choose “A percent” in the calculator to type it that way.
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