COUNTY · CA
San Mateo County, California
San Mateo County is a county in California with FIPS code 06081 and an estimated population of 726,353 (Census 2023), 15th largest of 58 in the state.
County facts
- Name
- San Mateo County
- State
- California
- Type
- county
- FIPS code
- 06081
- State FIPS
- 06
- Population (2023)
- 726,353
- Change since 2020
- -4.7%
- State rank
- 15 of 58
Population is the Census Bureau’s Vintage 2023 estimate.
Questions
What is the FIPS code for San Mateo County?
San Mateo County, California has the five-digit FIPS code 06081: 06 for the state and 081 for the county.
What state is San Mateo County in?
San Mateo County is in California.
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.