Where is the 857 area code?

Area code 857 covers Boston in Massachusetts, on Eastern Time.

What time zone is area code 857 in?

Numbers in the 857 area code sit in Eastern Time.

Is 857 a toll-free or scam area code?

No. 857 is a geographic North American Numbering Plan area code assigned to Massachusetts. Toll-free numbers use 800, 833, 844, 855, 866, 877 and 888. A call from 857 can still be spoofed, so treat unexpected calls with the usual caution.

Area code lookup

857 area code

Where the 857 area code is, which cities and counties it serves, the local time zone and the overlay codes dialled alongside it.

State: MA
Cities covered: 1
Counties: 1
Time zone: Eastern Time

Quick answer

Area code 857 serves Boston in Massachusetts. It sits in Eastern Time and covers 1 county and about 16 ZIP codes across the metros we track. Numbers there are also dialled as 339, 351, 508, 617, 774, 781, 978.

Cities in the 857 area code

Each city links to its full local profile: sales tax, housing, income and ZIP codes.

City	County	Time zone	ZIP codes
Boston, MA	Suffolk County	EST/EDT	16

Related area codes

Codes that share or border the same calling area.

857 area code FAQ

The questions people ask about this code.

Where is area code 857?

857 is a geographic area code in Massachusetts, covering Boston.

What time is it in the 857 area code?

857 observes Eastern Time (EST/EDT).

Is 857 a scam area code?

No — it is a normal geographic code, not a toll-free or premium-rate prefix. Caller ID can be spoofed on any code, so verify unexpected callers before sharing information.

Sources & transparency

North American Numbering Plan Administrator (NANPA) area code assignments — area code to geography mapping and overlay relationships
US Census Bureau, American Community Survey 2019-2023 5-year estimates — city, county and ZIP code geography

Last reviewed August 2026. Figures are published for reference and can change; verify with the source agency before filing or contracting. How we build and check this data.