ZIP Code 08540 — Princeton, NJ
08540 is a standard (street delivery) ZIP code serving Princeton, New Jersey, in Mercer 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 08540 at a glance
| ZIP code | 08540 |
|---|---|
| Primary city | Princeton |
| State | New Jersey (NJ) |
| County | Mercer FIPS 34021 |
| ZIP type | Standard (street delivery) |
| Time zone | America/New_York |
| Population | 50,388 |
| Coordinates | 40.364230, -74.656610 |
How ZIP+4 works in 08540
The four digits after the hyphen encode a delivery segment inside 08540. 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 08540 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.
Other ZIP codes in Princeton
Nearby ZIP codes
Showing the closest twelve. See every ZIP code within 25 miles of 08540.
| ZIP | City | Distance |
|---|---|---|
| 08542 | Princeton, NJ | 0.7 mi |
| 08544 | Princeton, NJ | 1.2 mi |
| 08553 | Rocky Hill, NJ | 2.6 mi |
| 08528 | Kingston, NJ | 2.6 mi |
| 08558 | Skillman, NJ | 4.2 mi |
| 08536 | Plainsboro, NJ | 4.3 mi |
| 08502 | Belle Mead, NJ | 5.8 mi |
| 08550 | Princeton Junction, NJ | 6.1 mi |
| 08852 | Monmouth Junction, NJ | 6.1 mi |
| 08648 | Lawrence Township, NJ | 6.5 mi |
| 08824 | Kendall Park, NJ | 6.7 mi |
| 08525 | Hopewell, NJ | 6.9 mi |
Questions about 08540
What is the ZIP+4 code for 08540?
08540 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 08540, you need to look up a specific street address to get them.
What city is 08540?
08540 is assigned to Princeton, New Jersey, in Mercer 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.