ZIP Code 45040 — Mason, OH
45040 is a standard (street delivery) ZIP code serving Mason, Ohio, in Warren 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 45040 at a glance
| ZIP code | 45040 |
|---|---|
| Primary city | Mason |
| State | Ohio (OH) |
| County | Warren FIPS 39165 |
| ZIP type | Standard (street delivery) |
| Time zone | America/New_York |
| Population | 59,518 |
| Coordinates | 39.350230, -84.309960 |
How ZIP+4 works in 45040
The four digits after the hyphen encode a delivery segment inside 45040. 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 45040 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 45040.
| ZIP | City | Distance |
|---|---|---|
| 45034 | Kings Mills, OH | 3.4 mi |
| 45039 | Maineville, OH | 4.3 mi |
| 45249 | Cincinnati, OH | 5.2 mi |
| 45065 | South Lebanon, OH | 5.3 mi |
| 45069 | West Chester, OH | 5.4 mi |
| 45241 | Cincinnati, OH | 7.1 mi |
| 45050 | Monroe, OH | 7.1 mi |
| 45140 | Loveland, OH | 7.4 mi |
| 45242 | Cincinnati, OH | 7.8 mi |
| 45044 | Middletown, OH | 7.8 mi |
| 45036 | Lebanon, OH | 8.2 mi |
| 45246 | Cincinnati, OH | 9.3 mi |
Questions about 45040
What is the ZIP+4 code for 45040?
45040 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 45040, you need to look up a specific street address to get them.
What city is 45040?
45040 is assigned to Mason, Ohio, in Warren 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.