Floor Area Ratio (FAR) Calculator ๐Ÿ“

Calculate the ratio of a building's total floor area to the lot area.

Lot Dimensions (in Feet)

Long side of the plot.

Short side of the plot.

Building Dimensions (Gross Floor Area)

Area of the ground floor.

Total floors (above grade).

Understanding Floor Area Ratio (FAR)

The **Floor Area Ratio (FAR)** is a zoning tool that regulates building density. It is defined as the ratio of the total floor area of a building (Gross Floor Area or GFA) to the area of the lot on which it's built.

The FAR Formula:

$$\text{FAR} = \frac{\text{Total Building Floor Area (GFA)}}{\text{Lot Area}}$$ FAR is expressed as a decimal ratio, such as $\mathbf{0.5}$ or $\mathbf{3.0}$.


Interpreting the Ratio

Low FAR (e.g., $0.5$)

  • **Meaning:** The GFA is half the lot area.
  • **Example:** A 2-story building that only covers 25% of the lot footprint.
  • **Typical Use:** Single-family residential zones and low-density areas.

High FAR (e.g., $3.0$+)

Meaning & Use

  • **Meaning:** The GFA is three or more times the lot area.
  • **Example:** A tall commercial building or apartment complex on a small urban lot.
  • **Typical Use:** Downtown commercial districts and high-density residential zones.

Zoning Note:

Municipalities establish a **maximum FAR** for each zoning district. Your calculated FAR must be equal to or less than the maximum allowed for your proposed development to be approved.