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 between September 23, 2026 and September 25, 2026.
Longmont, Colorado, in Boulder County, has about 100,000 residents (2024 Census Bureau estimate). A person kept in custody after an arrest in Longmont is held at the county jail, run by the Boulder 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: Longmont public records, Boulder County inmate search, Longmont arrest records, Longmont warrants, Longmont criminal records, Longmont court records, Colorado arrest records and Colorado inmate search.
Finding Someone in Custody in Longmont
The county jail, run by the Boulder County Sheriff's Office, holds everyone kept in custody after an arrest in Longmont, from every agency.
SearchSystems opened and checked the custody page of the Boulder County Sheriff's Office at bouldercounty.gov/safety/jail/listing-and-booking-reports (page title: Daily Booking and Listing Reports | Boulder County), phone 303-441-3600, 5600 Flatiron Parkway Boulder, CO 80301, Monday - Friday 8 a.m. - 5 p.m., which answered when SearchSystems opened it on September 23, 2026.
That page is the place to look for someone booked recently. A person cited and released at the scene, or held only a few hours by a city department, will not be on it.
The Boulder County Jail by the Numbers
On an average day in 2025 the jail held about 320 people, down from about 410 in 2019. Its rated capacity in 2025 was 543 beds, and it ran at 59 percent of it that year. The figures are from the Vera Institute of Justice's Incarceration Trends data.
Boulder County has about 330,000 residents (2024 Census Bureau estimate), so the jail holds about 10 people for every 10,000 residents.
Who Books People Into the Boulder County Jail
The Boulder County Sheriff's Office and the agency that reports for Longmont (filed by the FBI as Longmont Police Department) make the arrests that end in a booking in and around Longmont.
The FBI's agency list also places these agencies in Boulder County: Colorado Department of Revenue in Marijuana Enforcement Criminal Investigation, Boulder County (state agency); the University of Colorado at Boulder (campus police).
The Erie Police Department is listed by the FBI across two counties including Boulder County, so its arrests are not broken out for Boulder County here.
The largest arrest counts reported to the FBI were Boulder's 3,201 for 2025, Longmont's 2,378 for 2025 and the Boulder County Sheriff's Office's 1,242 for 2025.
Together, the five agencies in Boulder County with all twelve months of 2025 on file reported 7,765 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 Longmont arrest records.
From the Jail to State Prison
The jail holds people awaiting trial and people serving short sentences. A person sentenced to prison in Boulder County serves the sentence in a facility of the Colorado Department of Corrections, whose inmate locator is at cdoc.colorado.gov.
Frequently Asked Questions
How do I find an inmate in Longmont?
Look on the custody page of the Boulder County Sheriff's Office at bouldercounty.gov, or call 303-441-3600. It covers people booked into the county jail.
How many people are in the Boulder County jail?
About 320 on an average day in 2025, the latest year in the Vera Institute's jail data, against a rated capacity of 543 beds.
What is the phone number for the Boulder County jail?
303-441-3600, the number on the page of the Boulder County Sheriff's Office SearchSystems verified.
Where do people sentenced to prison in Boulder County go?
To a facility of the Colorado Department of Corrections; its inmate locator is at cdoc.colorado.gov.
Is this the official Longmont website?
No. SearchSystems.net is an independent public records guide, online since 1997. It links to the official city, county, court and state offices described above and does not hold records, charge for them or take requests.