Floor area ratio — almost always abbreviated as FAR— is the single number that determines how much building you can put on a piece of land. It's calculated by dividing total floor area by lot area, and it acts as a hard ceiling on density regardless of what the rest of the zoning code allows. Before you underwrite any development deal, FAR is the first number you need to pull.
The Basic Calculation
FAR is a ratio: total gross floor area of the building divided by the total area of the lot. If you have a 10,000 square foot lot and the zoning allows a FAR of 2.0, you can build up to 20,000 square feet of floor area. That could be a two-story building covering the entire lot, a four-story building covering half the lot, or any other combination that reaches the same total.
The key word is gross floor area. Most ordinances include all enclosed floor area measured from the exterior walls, including mechanical rooms, stairwells, and elevator shafts. Some jurisdictions exclude parking structures, mechanical floors, or basement areas — always check the definitions section of the ordinance before running your numbers.
Typical FAR Ranges by Zone Type
FAR limits vary enormously by district. Here are the ranges you'll encounter most often:
- R-1 single-family residential: 0.3 to 0.5. A 7,500 square foot lot in a standard R-1 zone allows only 2,250 to 3,750 square feet of building — less than many suburban homes already built there.
- R-2 and R-3 multifamily residential: 0.5 to 1.5, depending on the number of stories and density intended.
- Neighborhood commercial (C-1): 1.0 to 2.0. Usually designed for one- to two-story retail and office.
- General commercial (C-2): 1.5 to 4.0. Mid-rise mixed-use is common at the upper end.
- Downtown and urban core: 3.0 to 10.0 or higher. Major cities like New York, Chicago, and San Francisco allow FAR values of 12.0 or more in their densest districts with bonuses.
- Industrial: 0.5 to 1.5. Industrial zones often care more about lot coverage and setbacks than total floor area.
How FAR Interacts with Setbacks and Lot Coverage
Here's where most investors get tripped up: a high FAR doesn't mean you can actually build to it. Three separate constraints all apply simultaneously, and the most restrictive one wins.
Setbacksrequire building to be set back a minimum distance from each property line. On a 50-foot wide lot with 5-foot side setbacks, your buildable width is only 40 feet. That shrinks your floor plate before you've thought about FAR at all.
Lot coverage limits what percentage of the lot area can be covered by the building footprint — typically 40 to 60 percent in residential zones. If your lot is 5,000 square feet and coverage is capped at 50 percent, your footprint is at most 2,500 square feet regardless of FAR.
Height limits cap how many floors you can stack. A FAR of 3.0 on a 10,000 square foot lot gives you 30,000 square feet to play with. But if the height limit is 35 feet — roughly three stories — and your footprint after setbacks is 4,000 square feet, you can only build about 12,000 square feet. The FAR limit never comes into play.
This interaction is called the building envelope, and it's the actual box within which your structure must fit. In suburban residential zones, setbacks and lot coverage almost always bind before FAR does. In urban commercial and downtown zones, FAR is usually the true constraint.
Parking Often Binds Before FAR
In zones with surface parking requirements, parking can consume more land than the building itself and make a high FAR effectively unreachable. If a jurisdiction requires one parking space per 300 square feet of office and each surface space needs about 330 square feet including drive aisles, you're consuming almost as much land in parking as you're building above grade.
Structured parking — garages — partially solves this but adds significant cost. Parking minimums are being reduced or eliminated in many jurisdictions near transit, which is one reason transit-adjacent sites often carry premium values even when FAR hasn't changed.
Bonus FAR Provisions
Many ordinances allow developers to exceed base FAR limits in exchange for providing public benefits. Common bonus FAR provisions include:
- Affordable housing inclusion: Often the most valuable bonus. Cities like Seattle, Boston, and San Jose offer significant FAR increases — sometimes 50 to 100 percent above base — in exchange for a percentage of units at below-market rents.
- Public open space or plazas: Providing publicly accessible plazas, arcades, or through-block connections. New York's original 1961 zoning code famously offered bonus FAR for plazas; the result was a generation of cold, windswept spaces that are now largely discouraged.
- Green building certification: LEED Gold or Platinum, Passive House, or specific energy benchmarks can unlock bonus FAR in some jurisdictions.
- Affordable commercial space: Some cities offer bonuses for providing below-market commercial space for nonprofits or small businesses.
Bonus FAR is worth modeling carefully. The combination of density bonus plus the value of additional units often more than offsets the cost of the required benefit — which is exactly why cities use this mechanism rather than mandates.
How to Find FAR for Any Property
Start with the zoning map to identify the district, then go to the dimensional standards table in the zoning ordinance. FAR is usually listed alongside height limits, lot coverage, and setbacks in a single table. If you can't find the ordinance, Municode.com hosts the codes for thousands of US municipalities.
Be aware that overlay districts can modify base zone FAR. A property in a C-2 zone with a historic preservation overlay or a specific plan overlay may have a different effective FAR than the base C-2 standard. Always check for overlays after you've found the base zone.
FAR and Entitlement Value
When a project has already received approval to build at or above the base FAR — through a variance, planned development, or density bonus — that approval carries real value separate from the land itself. Entitlement value represents the gap between what the market will pay for an approved project and the cost of obtaining that approval. In tight markets with long entitlement timelines, this premium can be substantial.
For investors evaluating development sites, always calculate both the as-of-right FAR (what you can build without any approvals) and the potential FAR with bonuses. The spread between those two numbers is where discretionary risk and entitlement upside live.