28 ZIP Codes
| Zip Code | City | Population ↓ |
|---|---|---|
| 21702 | Frederick | 49,605 |
| 21701 | Frederick | 43,048 |
| 21703 | Frederick | 41,960 |
| 21771 | Mount Airy | 33,031 |
| 21704 | Frederick | 20,006 |
| 21774 | New Market | 17,134 |
| 21769 | Middletown | 11,965 |
| 21788 | Thurmont | 11,654 |
| 21793 | Walkersville | 10,719 |
| 21770 | Monrovia | 8,751 |
| 21754 | Ijamsville | 8,156 |
| 21716 | Brunswick | 7,200 |
| 21727 | Emmitsburg | 6,052 |
| 21755 | Jefferson | 5,909 |
| 21773 | Myersville | 5,826 |
| 21791 | Union Bridge | 5,340 |
| 21710 | Adamstown | 4,661 |
| 21758 | Knoxville | 4,409 |
| 21798 | Woodsboro | 2,928 |
| 21777 | Point Of Rocks | 2,462 |
| 21780 | Sabillasville | 2,159 |
| 21778 | Rocky Ridge | 745 |
| 21717 | Buckeystown | 245 |
| 21790 | Tuscarora | 170 |
| 21762 | Libertytown | 139 |
| 21718 | Burkittsville | 134 |
| 21714 | Braddock Heights | 95 |
| 21705 | Frederick | 6 |
The data shown reflect ZCTAs from the US Census. As of 2025, there are 28 ZCTAs in Frederick County, Maryland (US Census).