Paris Hilton may spend far less than 45 days in county jail for violating probation because of state policies and jail overcrowding, authorities said Thursday.

Hilton, sentenced last week to do the time, could spend three weeks or less behind bars because of a state requirement that grants inmates time off for good behavior and because of overcrowding in the system, Los Angeles County sheriff's spokesman Steve Whitmore said.

"It's possible that it could be 21 days, 23 days. It's a complicated formula that the state sets down. It's possible that she could do less time," Whitmore said.

As for overcrowding, "our jail is bursting at the seams" and some women inmates have been released after serving only 10 percent of their sentence, Whitmore said.

Last year, "Lost" actress Michelle Rodriguez was sentenced to 60 days in jail for violating probation after her drunken driving arrest in Hawaii. She was released in hours because of overcrowding.

Hilton's time will be determined when she is booked into the county system, Whitmore said.

She will not receive any favors because she is a celebrity, he added.

"She's going to be treated like any other low-level security risk."

A call to Hilton's publicist seeking comment was not immediately returned.

Hilton, 26, was sentenced last week for violating the terms of her probation in an alcohol-related reckless driving case. A judge ordered her to report to the women's jail in Lynwood by June 5.

Hilton intends to appeal and her fans have posted a petition on the Internet urging Gov. Arnold Schwarzenegger to pardon her.