Floor Area Ratio Calculator (USA)

For single-family homes in the US, FAR typically ranges from 0.15 to 0.50. For townhomes and small apartments, 0.5 to 2.0 is common. There’s no single “good” FAR — it depends on your zoning district, neighborhood context, and development goals. Higher FAR means more density, which may be desirable for rental income but less so for single-family character.

In most US jurisdictions, basements that are entirely below grade (ground level) are excluded from FAR calculations. However, if any portion of the basement extends above grade, that above-grade portion may be counted. NYC, for example, excludes fully below-grade cellars but counts basement areas that are more than 50% above grade. Always check your specific local zoning code.

Building beyond the permitted FAR requires either a zoning variance (granted by a Board of Adjustment/Zoning Appeals) or a special permit. Approval is not guaranteed and typically requires proving a hardship. Some cities offer FAR bonuses for including affordable housing units, green building features, or public amenities — for example, NYC’s Inclusionary Housing Program can provide up to 33% additional FAR.

Check these sources: (1) Your city or county zoning map to identify your zoning district, (2) The zoning ordinance text for that district’s FAR limit, (3) Many cities have online zoning lookup tools — search “[city name] zoning lookup” or “[city name] ZOLA” (Zoning and Land Use Application), (4) Call your local planning/zoning department directly. Some cities like NYC, LA, and Chicago have excellent online portals.

In most US jurisdictions, enclosed parking structures (both above and below ground) are excluded from FAR. However, open surface parking lots may be counted differently. Some cities like San Francisco have specific parking FAR exemptions. Check your local code’s definition of “gross floor area” for parking treatment.

FAR controls total bulk (how much floor area), while height limits control vertical extent (how tall). Both are separate zoning regulations. You can have a high FAR with a low height limit (requiring a wide, sprawling building) or a low FAR with a high height limit (a slender tower). Most zoning districts specify both independently.

Higher FAR typically increases land value because it permits more developable space. In real estate economics, land value is often expressed as “price per buildable square foot.” A lot with 10.0 FAR is inherently more valuable than the same-sized lot with 1.0 FAR, because you can build 10x more floor area. This is why downtown parcels command premium prices per square foot of land.

Attached garages are typically included in FAR because they’re part of the building’s gross floor area. Detached accessory structures (like a separate garage or shed) may or may not be included depending on local rules — many jurisdictions exclude structures under a certain size (e.g., under 200 sq ft or 1 story). Check your zoning code’s specific definitions.