28 zips
| Zip Code | City | Population ↓ |
|---|---|---|
| 21702 | Frederick | 47,437 |
| 21703 | Frederick | 41,766 |
| 21701 | Frederick | 41,340 |
| 21771 | Mount Airy | 32,827 |
| 21704 | Frederick | 19,623 |
| 21774 | New Market | 16,515 |
| 21769 | Middletown | 12,695 |
| 21788 | Thurmont | 11,919 |
| 21793 | Walkersville | 10,914 |
| 21770 | Monrovia | 7,815 |
| 21754 | Ijamsville | 7,439 |
| 21716 | Brunswick | 6,757 |
| 21727 | Emmitsburg | 6,079 |
| 21755 | Jefferson | 5,740 |
| 21773 | Myersville | 5,619 |
| 21710 | Adamstown | 4,901 |
| 21791 | Union Bridge | 4,734 |
| 21758 | Knoxville | 4,238 |
| 21798 | Woodsboro | 2,765 |
| 21777 | Point Of Rocks | 2,333 |
| 21780 | Sabillasville | 1,814 |
| 21778 | Rocky Ridge | 840 |
| 21717 | Buckeystown | 296 |
| 21762 | Libertytown | 176 |
| 21718 | Burkittsville | 142 |
| 21714 | Braddock Heights | 113 |
| 21790 | Tuscarora | 38 |
| 21705 | Frederick | 4 |
The data shown reflect ZCTAs from the US Census. As of 2024, there are 28 ZCTAs in Frederick County, Maryland (US Census).