The listing portals will tell you Old Westbury's median list price sat near $3.49 million in July 2026, with homes averaging roughly 195 days on market. Redfin put the May 2026 median sale at about $3.19 million on thin monthly volume. Those numbers are accurate, and they are also close to useless for deciding what to offer on any single property inside the village.
The reason is a zoning code most buyers never open. Old Westbury is not one market. It is three residential districts stacked inside 8.57 square miles, each with its own lot minimum, its own volume ceiling, and its own coverage cap. Two houses at the same price can represent very different assets once you read the district behind the address. The median tells you the mood of the room. The zoning tells you what you are actually paying for.
The number that hides the mechanism
Old Westbury's inventory skews long and lumpy. A single Daniel Gale listing on Spring Hill Lane is asking $28 million on roughly 6.8 acres. Another, at 6A Spring Hill Lane, is at $23 million on 92.7 acres. Meanwhile, a two-acre parcel on August Lane is listed near $3.7 million, and 120 Bacon Road at just over $5 million also sits on two acres. When a handful of trophy trades enter the sample, the year-over-year "median sale price" number can swing 40 to 55 percent without the underlying market moving at all.
What does move, and what a buyer can actually price against, is the build envelope permitted by the parcel's zoning district. That envelope is set in Chapter 216 of the Village Code, and it changes sharply as you move between the B, BB, and B-4 districts.
Three districts, three different assets
Here is the shape of the code, expressed as a buyer would want to read it.
| District | Minimum lot | Base building volume | Notes on scale |
|---|---|---|---|
| B (Article V) | 1 acre (43,560 sf) | 1.2 cubic feet per sf of lot up to the minimum; then 1 cf per 2.5 sf above | Legacy pre-1957 lots; 140-ft minimum frontage; principal dwelling height capped at 35 ft |
| BB (Article IV) | 2 acres (87,120 sf) | 78,000 cf at the minimum; then 1 cf per 2.5 sf of area beyond that | Peaked roof volume between 27 and 35 ft excluded from the calculation |
| B-4 (Article IVA) | 4 acres (174,240 sf) | Same 78,000 cf base at 87,120 sf, extended by lot-averaging formula | Principal plus accessory buildings capped at 6% of lot area; total structures plus paving capped at 25%; buildable circle of 350-ft diameter must fit entirely on the lot |
Read the third column carefully. The B-4 district is where most of Old Westbury's estate-scale properties sit, and the 6% building-area cap does something counterintuitive. As lot size grows, the maximum footprint grows in absolute square feet but the code still constrains the visual and structural density of the site. A four-acre B-4 lot is not "twice as much house" as a two-acre BB lot. It is a different product entirely, with more required setback, more required open space, and a required circular buildable envelope that many oddly shaped parcels cannot satisfy without variance.
Why the four-acre zone is not just bigger
Three provisions inside Article IVA are worth pricing into any B-4 offer:
The 6% cap on combined principal and accessory building area, and the separate 25% cap on all structures plus paved surfaces, together define how much pool, tennis court, motor court, guest cottage, and stable a buyer can legally add. On a four-acre lot, 6% is roughly 10,454 square feet of building footprint across every enclosed structure combined. If the existing house already uses 8,500, the "room to expand" a listing brochure describes may be smaller than it looks.
The 75-foot accessory setback in B-4 pushes pools, tennis courts, and barns well inside the property line. On lots between three and 3.99 acres created under the lot-averaging provision, that setback drops to 60 feet. This is where parcels look identical on a map and behave differently on a survey.
The 350-foot buildable circle is the one that catches out-of-village buyers. Article IVA requires that each B-4 lot contain a horizontal circle of at least 350 feet in diameter within which the principal building must sit. Long, narrow parcels can hit the four-acre threshold and still fail this test. Under the lot-averaging provisions of §216-22.13, that circle drops to 300 feet, which is one of the reasons Kean Development's Spring Hill at Old Westbury, an approximately 160-acre gated enclave, is subdivided the way it is.
A four-acre lot in Old Westbury is not defined by its acreage. It is defined by the largest circle you can draw inside its boundary.
Accessory uses, and the horses in the code
Article IV keeps horses as an accessory use in the B, BB, and B-4 districts at one horse per 20,000 square feet of lot area, with a hard ceiling of 30 horses regardless of acreage. Any building sheltering horses must sit at least 50 feet from any lot line, and manure storage must be enclosed and set 100 feet from any property line and 150 feet from a neighboring dwelling. For buyers reading the code as a lifestyle document, these are the sections that quietly explain why the equestrian character of the village has held for a century.
The four-district patchwork, and why the address matters more than the village
Old Westbury sits inside four separate school districts. The Village Resource Directory lists East Williston UFSD at 11 Bacon Road, Jericho UFSD at 99 Cedar Swamp Road, Roslyn UFSD at 300 Harbor Hill Road, and Westbury UFSD at 2 Hitchcock Lane. East Williston's The Wheatley School and Willets Road School both draw students from portions of the village, alongside East Hills, Roslyn Heights, and Mineola.
The relevance for a buyer is not which district is which. It is that district assignment changes parcel by parcel, and property tax burden shifts accordingly. Two houses one road apart can sit in different districts with different levies. This is a verification step, not a ranking exercise, and it is best confirmed at contract with the school district and the Nassau County Department of Assessment rather than trusted to a listing sheet.
What actually lives in the village
Old Westbury has no commercial zoning inside its boundaries. There is one restaurant in the village itself, the Old Westbury Diner. Daily commerce and dining pull residents outward: Americana Manhasset for luxury retail about five miles away, the historic Milleridge Inn in Jericho, Broadway Mall, and Roosevelt Field. Institutional acreage matters to the sense of scale as well. The New York Institute of Technology occupies the former Cornelius Vanderbilt Whitney estate, SUNY Old Westbury sits on a former estate parcel, and Old Westbury Gardens anchors the village's cultural identity. None of these show up on a comps sheet, but each shapes the reason large-lot zoning has held.
Six things to verify before writing an offer
- The zoning district of the specific parcel, confirmed against the Village Zoning Map, not inferred from the neighborhood.
- Remaining building-volume capacity under the district's cubic-foot formula, especially on lots with substantial existing accessory structures.
- Whether the parcel was created under §216-22.13 lot averaging, which changes accessory setbacks and buildable-circle requirements.
- School district assignment at the exact address, confirmed with the district and Nassau County.
- Existing coverage on the site, including all paved surfaces, measured against the 25% B-4 combined cap.
- Any variances of record from the Board of Zoning Appeals, which travel with the parcel and can materially expand or constrain future work.
FAQ
Why do year-over-year price changes swing so much in Old Westbury? Sale volume is thin. Realtytrac shows roughly 41 recorded transactions over a trailing 12-month window in 11568. When a single 10,000-square-foot estate closes, the median moves. Read the mix, not just the number.
Are two-acre and four-acre lots priced on a linear basis? No. The B-4 district's 6% building-area cap, 75-foot accessory setback, and 350-foot buildable-circle rule change what can be built and where. A B-4 parcel prices as a different asset class than a BB parcel, not as double the acreage.
Does the horse allowance apply to any parcel? The accessory horse use is available in the B, BB, and B-4 residence districts, subject to the one-horse-per-20,000-square-feet limit and the setback rules for stables and manure storage set out in Article IV.
If you are weighing an Old Westbury purchase against another North Shore village, or preparing to bring a parcel to market where the build envelope is doing quiet work under the price, Karen Sharf with Daniel Gale Sotheby's International Realty reads the code alongside the comps. Let's connect.
