Maryland · Eastern Time
Frederick, MD Area Codes
Frederick is served by 2 area codes (240, 301). Here's which is original, which are overlays, and how to pick one for a new local number.
Last updated June 5, 2026
Area codes serving Frederick
Frederick sits in Maryland, part of the South region and the Eastern Time zone. Its numbers are spread across an overlay of 2 codes that all cover the same ground: 240, 301.
The original code is 301. As the area ran low on numbers, regulators added overlay codes on top instead of splitting the city, so longtime residents kept their numbers while new lines received a newer code.
How to pick an area code for a new number
When you activate a new line in Frederick, the carrier assigns whichever code has numbers available — you usually can't choose. If a specific code matters to you (for example the prestige of 301), ask the carrier whether any blocks remain, or request a number transfer. All codes here dial identically and cost the same.
Dialing in Frederick
Because Frederick is an overlay area, 10-digit dialing is mandatory: always dial the area code plus the seven-digit number, even for a neighbor. See 10-digit dialing and overlay area codes for the background. For every code in Maryland, visit the Maryland area codes page.
Quick answers
Frederick area code FAQ
What area codes does Frederick use?
Frederick, MD is served by 2 area codes: 240, 301.
Which is the original Frederick area code?
301 is the original/primary code for Frederick; the others are overlays added later for more numbers.
Do I need to dial the area code in Frederick?
Yes. With multiple overlapping codes, 10-digit dialing is required for every call in this area.