ZIP Code 01581 — Westborough, MA
01581 is a standard (street delivery) ZIP code serving Westborough, Massachusetts, in Worcester 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 01581 at a glance
| ZIP code | 01581 |
|---|---|
| Primary city | Westborough |
| State | Massachusetts (MA) |
| County | Worcester FIPS 25027 |
| ZIP type | Standard (street delivery) |
| Time zone | America/New_York |
| Population | 21,944 |
| Coordinates | 42.268150, -71.614020 |
How ZIP+4 works in 01581
The four digits after the hyphen encode a delivery segment inside 01581. 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 01581 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 01581.
| ZIP | City | Distance |
|---|---|---|
| 01532 | Northborough, MA | 4.1 mi |
| 01536 | North Grafton, MA | 4.7 mi |
| 01772 | Southborough, MA | 4.8 mi |
| 01748 | Hopkinton, MA | 4.9 mi |
| 01545 | Shrewsbury, MA | 5.3 mi |
| 01519 | Grafton, MA | 5.7 mi |
| 01745 | Fayville, MA | 6 mi |
| 01568 | Upton, MA | 6.3 mi |
| 01752 | Marlborough, MA | 6.6 mi |
| 01560 | South Grafton, MA | 7.2 mi |
| 01721 | Ashland, MA | 7.5 mi |
| 01604 | Worcester, MA | 8 mi |
Questions about 01581
What is the ZIP+4 code for 01581?
01581 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 01581, you need to look up a specific street address to get them.
What city is 01581?
01581 is assigned to Westborough, Massachusetts, in Worcester 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.