FAR & Lot Coverage Calculator

Calculate Floor Area Ratio (FAR) and lot coverage percentage for zoning compliance. Free tool for architects, developers, and urban planners.

Calculate Floor Area Ratio (FAR) and lot coverage percentage for zoning and site planning. Enter your lot dimensions, building footprint, and floor areas to check compliance with local zoning regulations.

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What is Floor Area Ratio (FAR)?

Floor Area Ratio (FAR), also known as Floor Space Index (FSI) or Floor Space Ratio (FSR), is a key urban planning metric that measures the relationship between a building's total floor area and the size of the lot it sits on. A FAR of 1.0 means the total floor area equals the lot area. A FAR of 2.0 means the total floor area is twice the lot area, which could be a 2-story building covering the entire lot, or a 4-story building covering half the lot.

What is Lot Coverage?

Lot Coverage (also called Building Coverage or Site Coverage) is the percentage of a lot that is occupied by the building footprint. Unlike FAR, which considers all floors, lot coverage only looks at the ground-level footprint. Zoning codes typically limit lot coverage to ensure adequate open space, landscaping, parking, and stormwater management.

How to Use This Calculator

Enter your total lot area and select the unit (sq ft, m², or acres).
Enter the building footprint area (ground floor outline).
Add the area for each floor of the building. Click 'Add Floor' for multi-story buildings.
Optionally enter your local zoning FAR and lot coverage limits to check compliance.
Click 'Calculate' to see your FAR, lot coverage, and detailed breakdown.

Formulas Used

FAR = Total Floor Area ÷ Lot Area

Lot Coverage (%) = (Building Footprint ÷ Lot Area) × 100

Max Buildable Area = Lot Area × FAR Limit

Remaining Area = Max Buildable Area − Total Floor Area

Max Floors = Max Buildable Area ÷ Building Footprint

Common FAR Values by Zone

Rural / Agricultural: 0.1 – 0.3
Single-Family Residential: 0.3 – 0.7
Multi-Family Residential: 1.0 – 3.0
Neighborhood Commercial: 1.0 – 2.5
Downtown Commercial: 3.0 – 10.0
High-Density Urban Core: 10.0 – 25.0

Zoning & Planning Tips

FAR limits vary significantly by zone: residential areas may be 0.5–1.5, while commercial districts can be 5.0–15.0.
Lot coverage limits typically range from 25% to 80% depending on the zoning district.
Some jurisdictions exclude basements, parking garages, or mechanical spaces from FAR calculations.
Building setbacks, height restrictions, and lot coverage limits work together to shape building form.
Higher FAR values indicate denser development and are common in urban centers.
Always check your local zoning ordinance for specific FAR calculation rules and exemptions.

Common Applications

Zoning compliance verification for building permits
Feasibility studies for real estate development
Architectural site planning and massing studies
Urban density analysis and planning reviews
Property value and development potential assessment
Variance and rezoning application preparation