Maryland Area Codes
6 active area codes · Baltimore · Population around 6,245,314
Maryland has 6 active area codes, serving cities like Baltimore, Columbia, and Frederick. Of those, 6 are overlays covering ground another code already covers, which is why local calls there use all ten digits. The newest, 227, has been in service since June 14, 2023. Each code below links to its cities, carriers, timezone, and coverage map.
Maryland Area Code Map
What area codes does Maryland have?
- 227OverlayColumbiaVaries · 314 cities · 2,956,782
- 240OverlayGermantownEastern Time (ET) · 314 cities · 2,956,782
- 301OverlayGermantownEastern Time (ET) · 314 cities · 2,956,782
- 410OverlayBaltimoreEastern Time (ET) · 208 cities · 3,212,271
- 443OverlayBaltimoreEastern Time (ET) · 208 cities · 3,212,271
- 667OverlayBaltimoreEastern Time (ET) · 208 cities · 3,212,271
More than one of these codes covers 24 of the 24 counties in Maryland, and one county is covered by 6 of them. Each card counts the people inside that code's own boundary at the 2020 census. Adding all 6 gives 18,507,159, against the 6,177,224 the same census counts in those counties, because 12,329,935 residents fall inside more than one code.
Which cities are the largest in Maryland?
| # | City | Area Codes | Population |
|---|---|---|---|
| 1 | Baltimore | 410 / 443 / 667 | 568,271 |
| 2 | Columbia | 227 / 240 / 301 / 410 / 443 / 667 | 99,615 |
| 3 | Frederick | 227 / 240 / 301 | 89,537 |
| 4 | Germantown | 227 / 240 / 301 | 86,395 |
| 5 | Silver Spring | 227 / 240 / 301 | 71,452 |
| 6 | Gaithersburg | 227 / 240 / 301 | 70,686 |
| 7 | Rockville | 227 / 240 / 301 | 68,417 |
| 8 | Waldorf | 227 / 240 / 301 | 67,752 |
| 9 | Glen Burnie | 410 / 443 / 667 | 67,639 |
| 10 | Ellicott City | 410 / 443 / 667 | 65,834 |
How many phone prefixes does Maryland use?
The area codes in Maryland hold 3,460 assigned prefixes between them, listed under 76 distinct carrier names. A prefix is the three digits after the area code, and NANPA assigns each one to a single carrier. One of the 6 codes here — 227 — is newer than the NANPA extract behind these numbers, so its prefixes are not counted above.
Sources: City populations – U.S. Census Bureau PEP, Vintage 2024 (SUB-IP-EST2024-POP). State populations – the same program, Vintage 2025 (CO-EST2025-ALLDATA). Area-code footprint and county populations – 2020 Census Centers of Population, mapped against NANP area code boundaries. The share of each city inside a code is measured the same way, against Census place boundaries from the Census Bureau's TIGERweb service. Area code assignments – NANPA CO Code data. See our data methodology.
Frequently Asked Questions
How many area codes does Maryland have?
Maryland has 6 active area codes: 227, 240, 301, 410, 443, 667.
What is the main area code for Maryland?
Of the 6 area codes in Maryland, 410 is the oldest one still serving Baltimore, its largest city. 410 has been in service since October 6, 1991.
What are the largest cities in Maryland?
The largest cities in Maryland include Baltimore, Columbia, Frederick, Germantown, Silver Spring.
What is the total population of Maryland?
Maryland has an estimated total population of 6,245,314 based on US Census PEP 2024 data.
Do I have to dial ten digits in Maryland?
In the parts of Maryland covered by an overlay, yes. 6 of the 6 area codes here cover ground another code already covers, and where two codes share an area, local calls need the area code as well as the seven-digit number.
Why does Maryland have 6 area codes?
They arrived one at a time rather than all at once: 410 has been in service since October 6, 1991. 6 of the 6 are overlays, laid over a code that already covered the same ground instead of splitting its map in two. The most recent is 227, in service since June 14, 2023.
What is the newest area code in Maryland?
227, in service since June 14, 2023.
Is my county covered by more than one area code in Maryland?
It may be: more than one area code covers 24 of the 24 counties in Maryland, and one county there is covered by 6 of them. The table above shows which codes reach each of the largest cities.