Area codes in Frederick, Maryland
Frederick, Maryland uses 3 area codes — 301, 240 and 227. The main Frederick area code is 301.
Area codes serving Frederick
Phone numbers in Frederick are written as ten digits — for example (301) 555-0190 — and fall in the Eastern Time zone.
How Frederick came to have 3 area codes
The original Frederick area code is 301, in service since 1947. As the area ran low on available numbers, overlay codes were added over the same region for new phone lines: 240 (1997) and 227 (2023). Existing numbers kept their original code — an overlay never forces anyone to change their number — which is why Frederick now uses all 3 codes and every local call is dialed with ten digits.
All Maryland area codes · Is a Frederick call a scam?
Nearby cities
- Hagerstown area codes
- Rockville area codes
- Silver Spring area codes
- Fairfax area codes
- Washington area codes
- Baltimore area codes
- Alexandria area codes
- Manassas area codes
More cities in Maryland
Frequently asked questions
What is the area code for Frederick?
The main area code for Frederick, Maryland is 301. Frederick is now served by 3 area codes in total: 301, 240, 227.
How many area codes does Frederick have?
Frederick has 3 area codes: 301, 240, 227.
Why does Frederick have more than one area code?
As Frederick used up the numbers available in its original area code (301, in service since 1947), additional "overlay" codes were added over the same area so new phone numbers could keep being assigned.
How do you dial a Frederick number?
Dial all 10 digits — the area code (301 or 240 or 227) followed by the 7-digit local number. From abroad, dial +1, then the area code and number.
Sourced from the official NANPA (North American Numbering Plan Administrator) numbering database, current as of August 2, 2026. Refreshed monthly.