Definition
Floor area ratio (FAR) is a numerical standard that expresses the maximum allowable building floor area as a multiple of the lot area. It is calculated as:
FAR = Total Building Floor Area ÷ Lot Area
For example: a 10,000 square foot lot with an FAR of 2.0 can have a building with up to 20,000 square feet of total floor area. A single-story building would have to cover the entire lot (minus required setbacks). A two-story building covering half the lot would also hit the limit. A four-story building covering 25% of the lot would hit it too. FAR doesn't directly specify how tall a building can be — it limits how much space can be in it.
What FAR Controls
FAR is a bulk standard, not a use standard. It controls:
- The total amount of building on a lot (massing)
- How intensively a site can be developed
- In combination with height limits and setbacks, the overall three-dimensional envelope of development
It does not directly control what uses go in the building (that's governed by permitted use lists), parking requirements (those are separate standards), or design (which design review standards address).
FAR in Residential vs. Commercial Zones
FAR requirements vary dramatically by zone type:
- Single-family residential: Typical FARs of 0.3–0.5 (relatively low density)
- Multifamily residential: FARs of 1.0–2.5 depending on density targets
- Mixed-use/commercial corridors: FARs of 2.0–5.0
- High-density urban commercial: FARs of 5.0–15.0 or higher in major downtowns
FAR and California Housing Law
California's Density Bonus Law allows qualifying affordable housing projects to exceed the base FAR by the bonus percentage. A project receiving a 50% density bonus can also build 50% more floor area than the base FAR would otherwise allow. Additionally, California's objective design standards law (AB 2582) limits FAR as a tool to block qualifying housing projects.
FAR is a deceptively simple number that has major implications for housing production. Cities with low FAR limits in residential zones often find these limits are preventing density-bonus projects from reaching their full bonus allotment — creating a conflict with state Density Bonus Law. Legislaide identifies these conflicts as part of its municipal code compliance analysis.
Frequently Asked Questions
What is floor area ratio (FAR)?
Floor area ratio (FAR) is a zoning standard expressing the maximum allowable building floor area as a multiple of the lot area. An FAR of 2.0 on a 10,000 sq ft lot allows a building with up to 20,000 sq ft of total floor area, regardless of how many stories it has.
How is FAR calculated?
FAR equals total building floor area divided by lot area. For example: a 10,000 sq ft lot with an FAR of 1.5 allows up to 15,000 sq ft of floor area. That could be a 2-story building covering 75% of the lot, or a 3-story building covering 50%, or many other configurations.
What does FAR control vs. other zoning standards?
FAR controls building mass — the total amount of floor area on a lot. It does not directly control use (that's permitted uses), parking (a separate standard), or building design (design review). FAR works in combination with height limits and setbacks to create a three-dimensional development envelope.
How do typical FAR limits vary by zone type?
FAR limits vary widely: single-family residential zones typically allow 0.3–0.5; multifamily residential 1.0–2.5; mixed-use corridors 2.0–5.0; high-density urban commercial downtown zones 5.0–15.0 or higher. Higher FAR means more building mass is permitted on the same lot.
How does the Density Bonus Law affect FAR limits?
A density bonus project is entitled to exceed the base FAR by the applicable bonus percentage. A project receiving a 50% density bonus can build 50% more floor area than base FAR allows. FAR limits that prevent achieving the bonus density may be waivable under the Density Bonus Law's waiver provisions.
Published June 1, 2026 by Legal Team at Legislaide.