Math & Engineering
Floor Area Ratio (FAR) Calculator
Calculate the Floor Area Ratio (FAR) to determine building density and land use efficiency
Reviewed by the calculator.uk.com Team · Last reviewed 18 August 2026 · Our methodology
Enter values to calculate the Floor Area Ratio
Related to Floor Area Ratio (FAR) Calculator
The Floor Area Ratio (FAR) calculator is a fundamental tool in urban planning and real estate development that helps determine the density and intensity of land use. It calculates the relationship between a building's total floor area and the size of the lot it's built on. The calculation is straightforward: FAR is obtained by dividing the total floor area of the building by the total area of the lot.
The Formula
Floor Area Ratio (FAR) = Total Floor Area ÷ Lot Area
For example, if you have a building with a total floor area of 20,000 square feet on a lot that's 10,000 square feet, the FAR would be 2.0. This means the building's total floor area is twice the size of the lot. The calculator supports both square feet and square meters, allowing for flexibility in unit selection while maintaining accurate calculations.
Understanding your FAR result is crucial for urban planning and development decisions. The FAR value provides insights into building density and land use efficiency. Here's how to interpret different FAR values:
Common FAR Values
- FAR < 1.0: Building's floor area is less than the lot size (low-density development)
- FAR = 1.0: Building's floor area equals the lot size
- FAR > 1.0: Building's floor area exceeds the lot size (high-density development)
- FAR 2.0-5.0: Typical for urban commercial districts
- FAR > 5.0: Common in dense city centers with high-rise buildings
The FAR result helps planners, developers, and architects determine if a proposed building complies with local zoning regulations and whether it makes efficient use of the available land. Higher FARs generally indicate more intensive land use and are often found in urban centers, while lower FARs are typical in suburban or residential areas.
1. What is included in the total floor area calculation?
Total floor area typically includes all usable space within a building, including all stories above ground level. This usually encompasses interior floor space, but may exclude mechanical rooms, stairwells, elevator shafts, and parking areas, depending on local regulations.
2. Why is FAR important in urban planning?
FAR is a crucial zoning tool that helps control building density and urban development. It ensures consistent development patterns, manages population density, controls traffic impact, and helps maintain the desired character of neighborhoods while making efficient use of available land.
3. Can FAR requirements vary by location?
Yes, FAR requirements often vary significantly by location, zoning district, and land use type. Urban areas typically allow higher FARs to encourage density, while suburban or residential zones may have lower FAR limits to maintain a less intensive development pattern.
4. How can I increase my building's FAR?
FAR can be increased by adding more floors to a building, maximizing the buildable area on each floor, or through zoning bonuses that may be available in your jurisdiction. Some areas offer FAR bonuses for including certain amenities or meeting specific design criteria.
5. What is the scientific source for this calculator?
FAR itself is nothing more than a ratio, total floor area divided by lot area, a concept used throughout zoning codes rather than a formula requiring specialized derivation. What actually varies from place to place is the definition of "total floor area": which spaces count and which are excluded, such as mechanical rooms, stairwells, or below-grade parking, and that definition is set by each jurisdiction's own zoning ordinance rather than by one national or academic standard. Always check your local zoning code for its specific floor-area definition and permitted FAR before relying on this ratio for a real project.