Floor Area Ratio Calculator
Determine your property\'s Floor Area Ratio (FAR) and lot coverage. Enter lot dimensions, floor count, and per-floor area to calculate density metrics important for zoning and planning.
Length of the property/land
Width of the property/land
Total number of habitable stories
Square footage of each floor (assumed same for all floors)
What is Floor Area Ratio (FAR) and how is it calculated?
Floor Area Ratio (FAR) is the ratio of a building's total floor area to the size of the lot it sits on. FAR = Total Building Floor Area ÷ Lot Area. For example, a 4,000 sq ft building on a 10,000 sq ft lot has an FAR of 0.40. FAR is a zoning tool that controls building density. Higher FAR means more density. A 2-story building covering half the lot has the same FAR as a 1-story building covering the entire lot.
What is a good FAR for residential properties?
Typical FAR values by zone: Single-family residential: 0.3-0.6 (suburban), 0.5-1.0 (urban). Multi-family apartments: 0.8-2.0. Commercial/office: 1.0-5.0 (downtown areas can reach 10+). A standard suburban 1/4 acre lot (10,890 sq ft) with a 2,000 sq ft house has FAR = 0.18. Urban townhouses on small lots often have FAR of 1.0-1.5. Check your local zoning code—exceeding allowable FAR can prevent permit approval.
What is the difference between FAR, lot coverage, and building height?
FAR measures total floor area relative to lot size (all floors combined). Lot coverage (or building footprint) measures the percentage of the lot covered by the building's ground floor only. Building height limits how tall the structure can be. Example: on a 10,000 sq ft lot: 50% lot coverage = 5,000 sq ft ground floor. With 2 stories at FAR 1.0 = 10,000 sq ft total. FAR controls density, lot coverage controls open space, height controls massing.
How does FAR affect property value and development potential?
Higher FAR generally means more developable space and higher property value. A lot with FAR 2.0 can have twice the building area as one with FAR 1.0. However, higher FAR buildings cost more to construct (more floors, stronger structure, elevators). FAR also affects: daylight access to neighboring properties, street congestion, infrastructure demand, and neighborhood character. Many cities allow FAR bonuses for affordable housing, green building, or public amenities.