ZIP Codes in Longmont, CO
Longmont uses 3 ZIP codes, all in Boulder, Weld Counties. Pick one below for details, or look up the full nine-digit ZIP+4 for a specific street address.
All 3 Longmont ZIP codes
| ZIP | Type | County | Population |
|---|---|---|---|
| 80501 | standard | Boulder | 44,147 |
| 80503 | standard | Boulder | 35,846 |
| 80504 | standard | Weld | 63,451 |
Finding a ZIP+4 in Longmont
Knowing which of these 3 ZIP codes covers an address only gets you partway. The four-digit extension identifies the specific delivery point — typically one side of one block. Two houses facing each other on the same Longmont street almost always have different ZIP+4 codes even though they share all five leading digits.
Appending ZIP+4 to a mailing list?
Upload a CSV of Longmont addresses and download it complete.