Area code 240: Maryland
Area code 240 is a US state area code for Maryland, on Eastern Time. It has 785 prefixes in service across 63 rate centers, the largest being Washington Zone 03, Washington Zone 02 and Washington Zone 10. It shares its area with 227 and 301, so local numbers there can start with any of them.
Local time in area code 240
America/New_York
Prefixes in service
785 of 792 possible
63 rate centers
Area code 240 facts
| Location | Maryland, United States |
|---|---|
| Time zone | Eastern Time |
| Overlays | 227, 301 |
| Overlay of | 301 |
| In service since | June 1, 1997 |
| Local calls | 10 digits; toll calls 1 + 10 digits |
| Carrier | Not shown. An area code is where a number was issued; numbers port between carriers. Check line type |
Which cities and towns use area code 240?
NANPA records each prefix against a rate center, the local billing area a number belongs to, usually named after its main town. These are the 240 rate centers with the most prefixes in service. 51 smaller ones aren't listed.
| Rate center | Prefixes |
|---|---|
| Washington Zone 03 | 73 |
| Washington Zone 02 | 64 |
| Washington Zone 10 | 54 |
| Frederick | 43 |
| Gaithersburg | 40 |
| Laurel 236 | 39 |
| Hagerstown | 33 |
| Washington Zone 04 | 30 |
| Washington Zone 05 | 28 |
| Waldorf | 26 |
| Ashton 236 | 25 |
| Washington 236 Zone 13 | 18 |
Source: NANPA central office code assignments, file dated 10/17/2026. Each prefix holds up to 10,000 numbers.
How do I dial a 240 number?
NANPA's dialling plan for 240: local calls inside the code take 10 digits, toll calls 1 + 10 digits. From another area code, dial 1 first. From abroad, use +1. The examples use 555-0147, from a range reserved for fictional numbers.
| Local call inside 240 | 240-555-0147 |
|---|---|
| From another US or Canadian area code | 1-240-555-0147 |
| From outside North America | +1 240 555 0147 |
| E.164, for CRMs and SMS tools | +12405550147 |
When did area code 240 start?
Area code 240 went into service on June 1, 1997 as an overlay of 301. Today 240, 227 and 301 cover the same area as an overlay, which is why 10-digit dialling is needed for local calls there.
Tools for 240 numbers
- Area code lookup
Look up any code or a whole list of numbers, or find the codes for a state or city.
- Area code time zone
Local time for a list of numbers, with a callable-now flag.
- NPA-NXX lookup
Rate center and state for one prefix, a level below the area code.
- TCPA calling hours checker
Whether it's inside the federal 8 a.m. to 9 p.m. calling window there now.
Next step
A 240 number tells you where it was issued, not what it is now.
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Area code 240 questions
- What state is area code 240?
- Area code 240 is in Maryland, United States. Its largest rate centers by number of prefixes are Washington Zone 03, Washington Zone 02, Washington Zone 10, Frederick and Gaithersburg.
- What time zone is area code 240 in?
- Eastern Time.
- What area codes overlay 240?
- 227 and 301. An overlay adds a new code to the same area instead of splitting it, so neighbours can have different area codes and local calls need 10 digits.
- When did area code 240 start?
- Area code 240 went into service on June 1, 1997 as an overlay of 301.
- Is a 240 number a cell phone or a landline?
- The area code can't tell you. In the US and Canada mobiles, landlines and VoIP lines share area codes and prefixes, and numbers move between carriers and line types. Only a live line-type lookup answers it for one number.
- How many phone numbers does area code 240 have?
- 785 of its 792 possible prefixes are in service, and each prefix holds up to 10,000 numbers. That counts prefixes assigned to carriers, not numbers in use.
Other area codes in Maryland
Sources
Location, overlays, in-service date and dialling plan: NANPA NPA database, file dated 10/16/2026. Prefixes and rate centers: NANPA central office code assignments, 10/17/2026. Time zones mapped to the IANA time zone database. By the SimpleVerifier Team; how we build these pages.