Area Code 857

Massachusetts

Area code 857 serves Massachusetts, primarily Boston, in the Eastern Time (ET) time zone. It is an overlay area code sharing territory with area code 617.

Overlay Area Code

This area code is part of an overlay region, meaning the same geographic area is served by multiple area codes. Overlay codes were introduced to meet growing demand for phone numbers without requiring existing customers to change their numbers.

This area code shares its geographic region with: area code 617 (Boston).

In service since: 02-May-2001

Learn more about overlay and split area codes →

Demographics & Economics

Total Population: 1,482,537
Population Density: 3,754 people/sq mi
above U.S. average (U.S.: 93 people/sq mi)
Median Household Income: $92,859
above U.S. median (U.S.: $75,144)
Poverty Rate: 12.5%
near U.S. average (U.S.: 11.5%)
Unemployment Rate: 5.5%
above U.S. average (U.S.: 3.6%)
Education Attainment: Bachelor's Degree+
53.6%
above U.S. average (U.S.: 33.7%)
High School or Lower
24.8%

Statistics are population-weighted aggregations from Census ACS 5-year estimates. Population figures are approximate — see Sources & Methodology for details on how area code populations are derived.

See how this area code compares to all US area codes in the Statistics dashboard.

Time Zone

Eastern Time (ET)

NANPA Relief Status

According to the latest NANPA analysis (July 2026), this area code is not currently listed as exhausting within the next 36 months. No relief planning is in progress for this NPA.

Source: NANPA NPA Relief Planning Reports · See all relief planning statuses

Current Time

Eastern Time (ET)

Prefix Utilization

Geographic Coverage

State

Major Cities

Boston
Cambridge
Quincy
Newton
Somerville
Brookline
Everett
Chelsea
Milton
Belmont
South Boston
Watertown
Winthrop

Area Code 857 geographic coverage map (light mode)

History

Area code 857 serves as an overlay for the same territory as area code 617. It was introduced in 2001 to provide additional phone number capacity for the region. It shares its territory with area code area code 617.

Demographics

The estimated population served by area code 857 is approximately 1,482,537. The population density is 3,754 people per square mile, which is higher than the national average of 93. The median household income is $92,859, which is higher than the national median of $75,144. Approximately 53.6% of adults hold a bachelor's degree or higher, compared to the national rate of 33.7%. This rate is higher than the national average. The poverty rate stands at 12.5%, which is near the national rate of 11.5%.