COUNTY · CA

Contra Costa County, California

Contra Costa County is a county in California with FIPS code 06013 and an estimated population of 1,155,025 (Census 2023), 9th largest of 58 in the state.

County facts

Name: Contra Costa County
State: California
Type: county
FIPS code: 06013
State FIPS: 06
Population (2023): 1,155,025
Change since 2020: -0.9%
State rank: 9 of 58

Population is the Census Bureau’s Vintage 2023 estimate.

Other counties in California

Los Angeles County San Diego County Orange County Riverside County San Bernardino County Santa Clara County Alameda County Sacramento County All 58

Questions

What is the FIPS code for Contra Costa County?

Contra Costa County, California has the five-digit FIPS code 06013: 06 for the state and 013 for the county.

What state is Contra Costa County in?

Contra Costa 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.