ZIP Code 80303 — Boulder, CO
80303 is a standard (street delivery) ZIP code serving Boulder, Colorado, in Boulder 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 80303 at a glance
| ZIP code | 80303 |
|---|---|
| Primary city | Boulder |
| State | Colorado (CO) |
| County | Boulder FIPS 08013 |
| ZIP type | Standard (street delivery) |
| Time zone | America/Denver |
| Population | 24,996 |
| Coordinates | 39.974220, -105.212060 |
How ZIP+4 works in 80303
The four digits after the hyphen encode a delivery segment inside 80303. 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 80303 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 Boulder
Nearby ZIP codes
Showing the closest twelve. See every ZIP code within 25 miles of 80303.
| ZIP | City | Distance |
|---|---|---|
| 80305 | Boulder, CO | 2 mi |
| 80027 | Louisville, CO | 3 mi |
| 80310 | Boulder, CO | 3.4 mi |
| 80301 | Boulder, CO | 5.1 mi |
| 80025 | Eldorado Springs, CO | 5.5 mi |
| 80304 | Boulder, CO | 6.4 mi |
| 80026 | Lafayette, CO | 6.5 mi |
| 80007 | Arvada, CO | 7.5 mi |
| 80021 | Broomfield, CO | 7.7 mi |
| 80020 | Broomfield, CO | 7.9 mi |
| 80302 | Boulder, CO | 8.5 mi |
| 80544 | Niwot, CO | 9.1 mi |
Questions about 80303
What is the ZIP+4 code for 80303?
80303 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 80303, you need to look up a specific street address to get them.
What city is 80303?
80303 is assigned to Boulder, Colorado, in Boulder 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.