A Floor Area Ratio (FAR) Calculator helps you calculate the relationship between a building’s total gross floor area and its buildable land area. Enter both values to find the Floor Area Ratio.
FAR is commonly used in zoning, site planning, development analysis, and building design to understand the intensity of development on a site.
What Is Floor Area Ratio?
Floor Area Ratio, or FAR, compares the total floor area of a building with the buildable land area of its site.
A higher FAR generally means more building floor area is constructed on a given site. A lower FAR generally means less floor area relative to the available land area.
How to Use the Floor Area Ratio Calculator
Enter the following values:
- Gross floor area
- Buildable land area
Use the same unit for both values, such as square feet or square metres.
The calculator returns:
- Floor Area Ratio
Floor Area Ratio Formula
Divide the gross floor area by the buildable land area.
Floor Area Ratio=Buildable Land AreaGross Floor Area
Understanding Gross Floor Area
Gross floor area is the combined area of all floors in a building. Depending on the project and local rules, it may include or exclude areas such as basements, garages, balconies, stairs, mechanical rooms, and covered parking.
Use the gross floor area definition required by your local planning authority or project guidelines.
Understanding Buildable Land Area
Buildable land area is the area of land used for the calculation. It may refer to the entire plot area or only the buildable portion of a site, depending on local zoning and planning rules.
Use the land-area definition specified for your project.
Example FAR Calculation
Suppose a project has:
- Gross floor area: 10,000 square feet
- Buildable land area: 5,000 square feet
Floor Area Ratio=5000 ft210000 ft2
Floor Area Ratio=2
The Floor Area Ratio is 2. This means the total gross floor area is twice the size of the buildable land area.
What Does the FAR Value Mean?
- FAR = 1: Gross floor area equals the buildable land area.
- FAR greater than 1: Gross floor area is larger than the buildable land area, which is common for multi-storey buildings.
- FAR less than 1: Gross floor area is smaller than the buildable land area.
FAR does not describe the exact building shape, height, setbacks, open space, or lot coverage. These may be controlled by separate zoning requirements.
Important Notes
- Enter gross floor area and buildable land area using the same square unit.
- Verify which building areas are included in gross floor area for your location.
- Check whether your local authority uses total plot area or buildable land area for FAR.
- FAR limits, exemptions, and calculation methods can vary by zoning district and location.
- Use this calculator as a planning tool, not as a substitute for an official zoning determination.
Frequently Asked Questions
What does an FAR of 2 mean?
An FAR of 2 means the gross floor area is twice the buildable land area.
Can FAR be less than 1?
Yes. An FAR below 1 means the building’s gross floor area is smaller than the buildable land area.
What is the difference between FAR and lot coverage?
FAR compares the total floor area of all building levels with the land area. Lot coverage usually measures the ground area covered by the building footprint only.
Should I use square feet or square metres?
You can use either, as long as gross floor area and buildable land area use the same unit.
Does the calculator tell me the legal FAR limit?
No. The calculator calculates the FAR from the values entered. Check your local zoning rules, planning documents, or a qualified professional to confirm the allowed FAR for a specific site.
Is gross floor area always calculated the same way?
No. Local rules may include or exclude specific areas, such as garages, basements, balconies, stairs, or mechanical spaces. Use the definition required for your project.
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