ZIP Code 12123 — Nassau, NY
12123 is a standard (street delivery) ZIP code serving Nassau, New York, in Rensselaer County. To mail something here you only need these five digits — but the four-digit extension narrows delivery to a single point, and it is what USPS bulk postage discounts are priced on.
ZIP code 12123 at a glance
| ZIP code | 12123 |
|---|---|
| Primary city | Nassau |
| State | New York (NY) |
| County | Rensselaer FIPS 36083 |
| ZIP type | Standard (street delivery) |
| Time zone | America/New_York |
| Population | 4,457 |
| Coordinates | 42.522390, -73.606360 |
How ZIP+4 works in 12123
The four digits after the hyphen encode a delivery segment inside 12123. In practice one segment usually means:
- One side of one block — odd numbers on a street between two cross streets
- A single large building, or one floor of it
- A group of PO boxes, sometimes a single box
- A single business that receives enough mail to warrant its own code
That is why 12123 has no single ZIP+4: two neighbors across the street from each other usually have different ones. Enter a street address above and we will return the exact nine-digit code along with the standardized USPS address format.
Nearby ZIP codes
Showing the closest twelve. See every ZIP code within 25 miles of 12123.
| ZIP | City | Distance |
|---|---|---|
| 12063 | East Schodack, NY | 3.3 mi |
| 12132 | North Chatham, NY | 3.8 mi |
| 12115 | Malden Bridge, NY | 3.8 mi |
| 12024 | Brainard, NY | 4.6 mi |
| 12033 | Castleton On Hudson, NY | 5.1 mi |
| 12062 | East Nassau, NY | 5.4 mi |
| 12061 | East Greenbush, NY | 5.9 mi |
| 12130 | Niverville, NY | 6.2 mi |
| 12136 | Old Chatham, NY | 6.6 mi |
| 12184 | Valatie, NY | 7.3 mi |
| 12196 | West Sand Lake, NY | 7.5 mi |
| 12156 | Schodack Landing, NY | 7.6 mi |
Questions about 12123
What is the ZIP+4 code for 12123?
12123 is the five-digit ZIP code. The ZIP+4 adds four more digits that identify a specific delivery point — usually one side of a city block, a single building, or a group of PO boxes. Because those four digits change from address to address within 12123, you need to look up a specific street address to get them.
What city is 12123?
12123 is assigned to Nassau, New York, in Rensselaer County.
Do I need to use the ZIP+4?
It is optional for ordinary mail, but it speeds up sorting and it is required for most USPS bulk-mail postage discounts. Many address-verification and e-commerce systems also use ZIP+4 to confirm a delivery point exists.
Need thousands of these?
Upload a CSV and get ZIP+4, county, carrier route, and delivery-point data appended to every row — or call the API directly.