FAR (Floor Area Ratio)
The ratio of a building's total floor area to the area of the lot it sits on. FAR caps how much building a site can hold, independent of how tall or wide it is.
What it means
Floor Area Ratio is a single number: total building floor area divided by lot area. A 10,000-square-foot lot with a FAR limit of 2.0 can hold 20,000 square feet of floor area.
What makes FAR distinct from height or lot coverage limits is that it regulates bulk without dictating shape. That same 20,000 square feet could be a two-story building covering the whole lot, or a four-story building covering half of it. FAR sets the total; other standards constrain the form.
The definition of floor area is where the real work is. Ordinances differ on whether to count basements, parking structures, mechanical space, balconies, or areas below a stated ceiling height. Two cities with an identical FAR number can permit noticeably different buildings purely because of how each defines the numerator.
Some cities also offer FAR bonuses — additional floor area granted in exchange for affordable units, public open space, or historic preservation.
Why it matters
FAR is usually the binding constraint on development capacity in denser districts, which makes it the number that drives feasibility. For anyone underwriting a site, it translates fairly directly into how much sellable or leasable area a parcel can support.
Because the definition of floor area is technical and city-specific, FAR is also easy to get wrong from the outside. An assumption carried over from another jurisdiction — that structured parking is exempt, say — can move a pro forma by a full floor.
An example
A 20,000-square-foot parcel is zoned for a FAR of 1.5, giving 30,000 square feet of permitted floor area. The developer wants ground-floor retail plus three residential floors. If the city excludes below-grade parking from floor area, the full 30,000 goes to occupied space. If it does not, and the garage is 8,000 square feet, only 22,000 remains — roughly a floor of apartments gone, decided entirely by a definition.
How Conflation Labs fits in
Getting FAR right means reading the ordinance's own definition of floor area, not a general one. Our Zoning Research Agent answers capacity questions from the adopted text and cites the definition it applied, so the exclusions are visible rather than assumed. For teams running this across many parcels, the Zoning Workspace keeps that work in one place.
Where this comes up in our work
Common questions
No. Lot coverage measures the building's footprint as a share of the lot — a two-dimensional constraint. FAR measures total floor area across all stories. A building can satisfy one and violate the other, and most projects are limited by whichever binds first.
No. Plenty of low-density residential districts control bulk through height, setbacks, and coverage instead, and never mention FAR. It appears most often in commercial, mixed-use, and higher-density residential districts.