ZIP Code 02451 — Waltham, MA
02451 is a standard (street delivery) ZIP code serving Waltham, 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 02451 at a glance
| ZIP code | 02451 |
|---|---|
| Primary city | Waltham |
| State | Massachusetts (MA) |
| County | Middlesex FIPS 25017 |
| ZIP type | Standard (street delivery) |
| Time zone | America/New_York |
| Population | 17,393 |
| Coordinates | 42.398590, -71.257300 |
How ZIP+4 works in 02451
The four digits after the hyphen encode a delivery segment inside 02451. 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 02451 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 Waltham
Nearby ZIP codes
Showing the closest twelve. See every ZIP code within 25 miles of 02451.
| ZIP | City | Distance |
|---|---|---|
| 02452 | Waltham, MA | 1.9 mi |
| 02453 | Waltham, MA | 2.2 mi |
| 02421 | Lexington, MA | 2.9 mi |
| 01773 | Lincoln, MA | 3.3 mi |
| 02493 | Weston, MA | 3.5 mi |
| 02466 | Auburndale, MA | 3.7 mi |
| 02465 | West Newton, MA | 3.7 mi |
| 02478 | Belmont, MA | 4 mi |
| 02460 | Newtonville, MA | 4.1 mi |
| 02476 | Arlington, MA | 4.4 mi |
| 02472 | Watertown, MA | 4.5 mi |
| 02420 | Lexington, MA | 4.6 mi |
Questions about 02451
What is the ZIP+4 code for 02451?
02451 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 02451, you need to look up a specific street address to get them.
What city is 02451?
02451 is assigned to Waltham, 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.