ZIP Codes in Frederick, MD
Frederick uses 5 ZIP codes, all in Frederick County. Pick one below for details, or look up the full nine-digit ZIP+4 for a specific street address.
All 5 Frederick ZIP codes
| ZIP | Type | County | Population |
|---|---|---|---|
| 21701 | standard | Frederick | 43,048 |
| 21702 | standard | Frederick | 49,605 |
| 21703 | standard | Frederick | 41,960 |
| 21704 | standard | Frederick | 20,006 |
| 21705 | standard | Frederick | 6 |
Finding a ZIP+4 in Frederick
Knowing which of these 5 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 Frederick 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 Frederick addresses and download it complete.