Blog · Zoning
What Is Floor Area Ratio (FAR)? A Complete Guide With Examples
Landon Reid · Founder, Buildability™2026-05-01 · 7 min
TL;DR: Floor Area Ratio (FAR) is total building floor area divided by lot area. A FAR of 0.5 on a 10,000 sqft lot lets you build up to 5,000 sqft of floor space. FAR is the primary number that controls maximum building size in most U.S. zoning codes. Single-family residential zones typically allow 0.3–0.6 FAR. Mid-rise mixed-use zones allow 2.0–4.0. Manhattan's densest commercial zones go above 15.0. FAR is enforced separately from height and lot coverage, which is why all three matter and why you cannot eyeball maximum building size from any one of them.
How to calculate FAR
The formula is simple:
FAR = total building floor area ÷ lot area
Both numbers are measured in the same units (typically square feet in the U.S.). FAR has no units — it is a pure ratio.
Worked example 1: single-family lot
A 7,200 sqft suburban lot zoned R-1 with a 0.5 FAR limit allows a maximum of:
7,200 × 0.5 = 3,600 sqft of total building floor area
That 3,600 sqft includes the main house plus any detached garage, ADU, or accessory structure that counts toward FAR. The exact rules for what counts vary by city — see "What counts toward FAR" below.
Worked example 2: urban infill lot
A 4,000 sqft Los Angeles lot zoned R-3 with a 1.5 FAR limit allows:
4,000 × 1.5 = 6,000 sqft of total building floor area
Stacked across two or three stories, this is enough for a small apartment building. Combined with state-mandated ADU bonuses (California density bonus law), the effective FAR can be higher.
Worked example 3: dense commercial
A 10,000 sqft midtown Manhattan lot zoned C5-3 with a 10.0 FAR limit allows:
10,000 × 10 = 100,000 sqft of total floor area
That is what enables Manhattan's tower-on-podium typology. With air-rights transfers, individual lots can effectively exceed their base FAR.
Why FAR is the most important number on your zoning report
Three reasons:
1. It is the single best predictor of buildable size. Height and lot coverage limits set a maximum envelope; FAR sets a maximum amount of building. A high lot coverage with a low FAR (a wide one-story footprint) and a low lot coverage with a high FAR (a tall narrow tower) can yield the same FAR but fundamentally different projects. FAR is what compares apples to apples.
2. It compounds with bonuses. Most cities offer FAR bonuses for affordable housing, transit-oriented development, public open space, or historic preservation. These bonuses can push effective FAR 25–50% above the base. Knowing the base FAR is the start; knowing what bonuses are available on your parcel is the real edge.
3. It is what financial models care about. Construction lenders underwrite to gross buildable square footage. Pro formas size revenue against rentable square feet. Both numbers derive from FAR before they derive from anything else.
What counts toward FAR (and what doesn't)
This is where every project gets surprises. The general rules:
| Counts toward FAR (typical) | Does NOT count toward FAR (typical) |
|---|---|
| Conditioned above-grade floor area | Open balconies and decks |
| Mezzanines and lofts | Most rooftop mechanical rooms |
| Enclosed garages | Carports (varies by city) |
| Detached ADUs (in many cities) | Below-grade basements (in many cities) |
| Habitable attics | Crawl spaces |
Cities differ on every line in this table. Notable variations:
- New York measures Floor Area in a way that excludes mechanical, parking below grade, and certain stair towers — pushing effective FAR higher than the headline number suggests.
- Los Angeles counts ADUs against base FAR for some zones but waives them under state ADU law up to 800 sqft.
- Boston has a "useable floor area" definition that excludes some attic and basement space.
The right move: get the actual zoning code definition for your city before you size a project. Buildability™ pulls this for you in the property report.
FAR ranges by zone type
Approximate ranges across major U.S. cities. Your city's specific numbers will vary.
| Zone type | Typical FAR range | Notes |
|---|---|---|
| Rural / agricultural | 0.05–0.15 | FAR rarely binding; lot size minimums dominate |
| Single-family residential (R-1) | 0.3–0.6 | Often layered with lot coverage limits |
| Two-family / townhouse (R-2, R-3) | 0.5–1.5 | Boost from ADU bonuses possible |
| Multi-family low-rise (R-4 / RM) | 1.0–3.0 | Where the bulk of mid-density infill happens |
| Neighborhood commercial (C-1) | 0.5–2.0 | Often dual-use limited |
| General commercial / mixed-use | 2.0–5.0 | The 5-over-1 typology lives here |
| Downtown / dense commercial | 5.0–15.0 | Bonusable in transit zones |
| Manhattan high-density commercial | 10.0–18.0 | Plus air-rights transfers |
These are ranges — exact FAR is set per zone in your city's ordinance.
FAR vs. lot coverage vs. height — they all matter
A common mistake is treating these three controls as redundant. They aren't. Each binds separately, and your buildable size is the intersection of all three.
| Control | What it limits | How it binds |
|---|---|---|
| FAR | Total floor area | Compounds across stories |
| Lot coverage | Footprint of building on the ground | Limits how much of the lot is built on |
| Height | Vertical envelope | Caps building height in feet or stories |
Worked example: a 5,000 sqft lot with 0.6 FAR, 40% lot coverage, 35 ft height limit allows:
- FAR: 3,000 sqft of total floor area
- Lot coverage: 2,000 sqft footprint
- Height: ~3 stories at standard residential floor heights
The binding constraint is the smallest implied building — in this case lot coverage with stacked stories, since a 2,000 sqft footprint over 1.5 stories yields 3,000 sqft (matching the FAR cap exactly). Often two of the three constraints will conflict, and the smaller one wins.
Frequently asked questions
What does a FAR of 1.0 mean?
A FAR of 1.0 means your maximum total building floor area equals your lot area. On a 5,000 sqft lot, you could build up to 5,000 sqft of total floor area — for example a 2,500 sqft footprint over two stories, or a 1,667 sqft footprint over three stories.
What is a good FAR for residential property?
For single-family residential, 0.4–0.6 is typical and yields a comfortable house on a standard suburban lot. For multi-family, 1.5–2.5 is the sweet spot for the 4-to-6-unit "small multifamily" typology that lenders are most comfortable with.
Does basement square footage count toward FAR?
Usually no, if it is fully below grade. Once any portion of the basement is more than ~3-4 feet above grade (varies by city), it begins counting. Walk-out basements often partially count.
How do I find the FAR for my property?
The fastest way is the Buildability™ zoning lookup — FAR is included in the standard report. Manually: find your zoning code on your city's zoning map, then look up the dimensional standards table in the city's zoning ordinance. The FAR is listed alongside setbacks, height, and lot coverage for each zone.
Can I get a FAR bonus?
In many cities, yes. Common bonus paths: affordable housing set-asides (typically +20–35% FAR), transit-oriented development overlays (+25–50% near rail stations), historic preservation, public open space dedications, and green-building certifications. The bonuses are listed in the zoning code or in a separate density bonus chapter.
Is FAR the same as floor space ratio (FSR)?
Yes — "FSR" is a regional name (common in Vancouver, Toronto, Sydney) for the same calculation. Some U.S. cities use "Floor-Area Ratio" or "FAR" interchangeably with "Plot Ratio" or "Building Bulk." All measure the same thing.