COUNTY · MA

Suffolk County, Massachusetts

Suffolk County is a county in Massachusetts with FIPS code 25025 and an estimated population of 768,425 (Census 2023), 4th largest of 14 in the state.

County facts

Name: Suffolk County
State: Massachusetts
Type: county
FIPS code: 25025
State FIPS: 25
Population (2023): 768,425
Change since 2020: -3.6%
State rank: 4 of 14

Population is the Census Bureau’s Vintage 2023 estimate.

Major cities in Suffolk County

Boston

Other counties in Massachusetts

Middlesex County Worcester County Essex County Norfolk County Bristol County Plymouth County Hampden County Barnstable County All 14

Questions

What is the FIPS code for Suffolk County?

Suffolk County, Massachusetts has the five-digit FIPS code 25025: 25 for the state and 025 for the county.

What state is Suffolk County in?

Suffolk County is in Massachusetts.

How do I know if an address is in this county?

Use the address lookup. ZIP codes and city names can cross county lines, so an address is the reliable check.

Sources: U.S. Census Bureau geographic reference files; Census Bureau Population Estimates, Vintage 2023. Last reviewed 2026-10-27.