ZIP Code 80503 — Longmont, CO
80503 is a standard (street delivery) ZIP code serving Longmont, 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 80503 at a glance
| ZIP code | 80503 |
|---|---|
| Primary city | Longmont |
| State | Colorado (CO) |
| County | Boulder FIPS 08013 |
| ZIP type | Standard (street delivery) |
| Time zone | America/Denver |
| Population | 35,846 |
| Coordinates | 40.169220, -105.207250 |
How ZIP+4 works in 80503
The four digits after the hyphen encode a delivery segment inside 80503. 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 80503 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 Longmont
Nearby ZIP codes
Showing the closest twelve. See every ZIP code within 25 miles of 80503.
| ZIP | City | Distance |
|---|---|---|
| 80544 | Niwot, CO | 4.9 mi |
| 80501 | Longmont, CO | 5.6 mi |
| 80301 | Boulder, CO | 8.4 mi |
| 80504 | Longmont, CO | 9.3 mi |
| 80304 | Boulder, CO | 9.6 mi |
| 80513 | Berthoud, CO | 10.3 mi |
| 80455 | Jamestown, CO | 10.5 mi |
| 80540 | Lyons, CO | 10.7 mi |
| 80310 | Boulder, CO | 11.7 mi |
| 80542 | Mead, CO | 11.9 mi |
| 80026 | Lafayette, CO | 12.3 mi |
| 80302 | Boulder, CO | 12.3 mi |
Questions about 80503
What is the ZIP+4 code for 80503?
80503 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 80503, you need to look up a specific street address to get them.
What city is 80503?
80503 is assigned to Longmont, 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.