ZIP Code 11787 — Smithtown, NY
11787 is a standard (street delivery) ZIP code serving Smithtown, New York, in Suffolk 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 11787 at a glance
| ZIP code | 11787 |
|---|---|
| Primary city | Smithtown |
| State | New York (NY) |
| County | Suffolk FIPS 36103 |
| ZIP type | Standard (street delivery) |
| Time zone | America/New_York |
| Population | 34,499 |
| Coordinates | 40.853380, -73.210890 |
How ZIP+4 works in 11787
The four digits after the hyphen encode a delivery segment inside 11787. 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 11787 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 11787.
| ZIP | City | Distance |
|---|---|---|
| 11788 | Hauppauge, NY | 2.4 mi |
| 11754 | Kings Park, NY | 3 mi |
| 11780 | Saint James, NY | 3.4 mi |
| 11767 | Nesconset, NY | 3.5 mi |
| 11725 | Commack, NY | 3.8 mi |
| 11749 | Islandia, NY | 3.8 mi |
| 11722 | Central Islip, NY | 4.9 mi |
| 11755 | Lake Grove, NY | 4.9 mi |
| 11717 | Brentwood, NY | 5.2 mi |
| 11731 | East Northport, NY | 5.6 mi |
| 11790 | Stony Brook, NY | 5.7 mi |
| 11779 | Ronkonkoma, NY | 5.7 mi |
Questions about 11787
What is the ZIP+4 code for 11787?
11787 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 11787, you need to look up a specific street address to get them.
What city is 11787?
11787 is assigned to Smithtown, New York, in Suffolk 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.