Reviewed and updated October 9, 2026 by the SearchSystems.net editorial team. The arrest counts are the ones each agency reported to the FBI, as the FBI held them on October 8, 2026. The jail figures are from the Vera Institute of Justice's Incarceration Trends data. Every office link was opened and checked against the office's own site on September 23, 2026.
Contra Costa County, California, has about 1.2 million residents (2024 Census Bureau estimate). A person kept in custody after an arrest in Contra Costa County is held at the county jail, run by the Contra Costa County Sheriff's Office, and the jail's record of each person held is a public record. This guide says where to look for someone in custody, what the jail holds and who books people into it.
This guide covers the search, the jail, who books people, state prison and common questions.
Related guides: Contra Costa County public records, Contra Costa County arrest records, Contra Costa County warrants, Contra Costa County criminal records, Contra Costa County court records, California arrest records and California inmate search.
Finding Someone in Custody in Contra Costa County
The county jail, run by the Contra Costa County Sheriff's Office, holds everyone kept in custody after an arrest in Contra Costa County, from every agency.
SearchSystems opened and checked the custody page of the Contra Costa County Sheriff's Office at cocosheriff.org/how-do-i/inmate-information (page title: Inmate Information | Contra Costa Sheriff, CA), which answered when SearchSystems opened it on September 23, 2026.
Someone booked recently shows on that page; someone cited and released at the scene, or held a few hours at a city station, does not.
The Contra Costa County Jail by the Numbers
On an average day in 2025 the jail held about 940 people, down from about 1,200 in 2019. Its rated capacity in 2023, the last year with a capacity figure, was 1,831 beds, and it ran at 49 percent of it that year. The figures are from the Vera Institute of Justice's Incarceration Trends data.
Contra Costa County has about 1.2 million residents (2024 Census Bureau estimate), so the jail holds about 8 people for every 10,000 residents.
Who Books People Into the Contra Costa County Jail
The Contra Costa County Sheriff's Office and the agencies that report for Concord, Antioch, Richmond, San Ramon, Pittsburg, Walnut Creek and 13 more cities make the arrests that end in a booking in Contra Costa County.
The FBI's agency list also places two other agencies, one campus police department and one state police unit in Contra Costa County (the arrest records guide names each one).
The largest arrest counts reported to the FBI were Concord's 2,991 for 2025, the Contra Costa County Sheriff's Office's 1,973 for 2025 and Richmond's 1,714 for 2025.
Together, the 21 agencies in Contra Costa County with all twelve months of 2025 on file reported 17,288 arrests to the FBI that year. Those kept in custody were booked into the county jail; a person cited and released at the scene was not.
The counts, agency by agency and year by year, are in Contra Costa County arrest records.
From the Jail to State Prison
A sentence of more than a year is served in state prison, not the jail; the California Department of Corrections and Rehabilitation lists its inmates at cdcr.ca.gov/search.
Frequently Asked Questions
How do I find an inmate in Contra Costa County?
Look on the custody page of the Contra Costa County Sheriff's Office at cocosheriff.org/how-do-i/inmate-information. It covers people booked into the county jail.
How many people are in the Contra Costa County jail?
About 940 on an average day in 2025, the latest year in the Vera Institute's jail data, against a rated capacity of 1,831 beds.
Where do people sentenced to prison in Contra Costa County go?
To a facility of the California Department of Corrections and Rehabilitation; its inmate locator is at cdcr.ca.gov/search.
Is this the official Contra Costa County website?
No. SearchSystems.net is an independent public records guide, online since 1997. It links to the official county, court and state offices described above and does not hold records, charge for them or take requests.