ZIP Code 02138 — Cambridge, MA
02138 is a standard (street delivery) ZIP code serving Cambridge, Massachusetts, in Middlesex 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 02138 at a glance
| ZIP code | 02138 |
|---|---|
| Primary city | Cambridge |
| State | Massachusetts (MA) |
| County | Middlesex FIPS 25017 |
| ZIP type | Standard (street delivery) |
| Time zone | America/New_York |
| Population | 38,509 |
| Coordinates | 42.379970, -71.134460 |
How ZIP+4 works in 02138
The four digits after the hyphen encode a delivery segment inside 02138. 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 02138 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 Cambridge
Nearby ZIP codes
Showing the closest twelve. See every ZIP code within 25 miles of 02138.
| ZIP | City | Distance |
|---|---|---|
| 02140 | Cambridge, MA | 0.9 mi |
| 02163 | Boston, MA | 1 mi |
| 02134 | Allston, MA | 1.5 mi |
| 02144 | Somerville, MA | 1.6 mi |
| 02143 | Somerville, MA | 1.9 mi |
| 02139 | Cambridge, MA | 2 mi |
| 02472 | Watertown, MA | 2.3 mi |
| 02135 | Brighton, MA | 2.3 mi |
| 02145 | Somerville, MA | 2.4 mi |
| 02478 | Belmont, MA | 2.6 mi |
| 02446 | Brookline, MA | 2.6 mi |
| 02141 | Cambridge, MA | 2.7 mi |
Questions about 02138
What is the ZIP+4 code for 02138?
02138 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 02138, you need to look up a specific street address to get them.
What city is 02138?
02138 is assigned to Cambridge, Massachusetts, in Middlesex 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.