South region · Eastern Time
Maryland Area Codes
All 6 area codes serving Maryland, the cities each one covers, and which are overlays. Maryland is served by 6 area codes in the Eastern Time zone.
Last updated October 3, 2026
Full list
Every Maryland area code
Maryland is served by 6 area codes in the Eastern Time zone. 4 of these are overlay codes layered over busy metros; the rest are geographic codes.
| Code | Area served | Type | In service |
|---|---|---|---|
| 227 | Western Maryland and the Washington, D.C. suburbs in Montgomery and Prince George's counties | Overlay | Since 2023 |
| 240 | Western Maryland and the Washington, D.C. suburbs in Montgomery and Prince George's counties | Overlay | Since 1997 |
| 301 | Western Maryland and the Washington, D.C. suburbs in Montgomery and Prince George's counties | Geographic | Since 1947 |
| 410 | Baltimore metro and the rest of eastern Maryland, including the Eastern Shore | Geographic | Since 1991 |
| 443 | Baltimore metro and the rest of eastern Maryland, including the Eastern Shore | Overlay | Since 1997 |
| 667 | Baltimore metro and the rest of eastern Maryland, including the Eastern Shore | Overlay | Since 2012 |
Area codes and dialing in Maryland
Maryland's 6 area codes mix older geographic codes with newer overlays. The busiest metros — around Frederick, Baltimore — carry the most numbers and rely on overlays, which is why 10-digit dialing is required there. Quieter parts of the state may still use a single code. The oldest code in Maryland is 301 (Frederick), one of the original 1947 area codes.
Whenever a Maryland region runs low on numbers, a new overlay is added on top rather than splitting the map, so existing customers keep their numbers. See 10-digit dialing for what that means in practice, or the newest area codes for upcoming changes.
Maryland city area code pages
Look up the area codes for a specific Maryland city: Baltimore · Frederick · Annapolis.
Browse Maryland another way
Explore by South region, by time zone, or jump to the city index. You can also see the complete numeric list of every US area code.
Quick answers
Maryland area code FAQ
How many area codes does Maryland have?
Maryland currently has 6 area codes: 227, 240, 301, 410, 443, 667.
What is the main area code for Maryland?
Maryland has no single main code. Its original 1947 area code was 301; today the main cities are served by 301 (Frederick), 410 (Baltimore), 240 (Frederick), 443 (Baltimore), 667 (Baltimore).
Does Maryland require 10-digit dialing?
Yes, in its overlay areas you must dial all 10 digits, even for local calls. Dialing all 10 digits always works, so it is the safe habit.