Superior Court Judge Cynthia Rayvis ordered the sentence after authorities said they found methamphetamine in the actor's car May 8 in Bakersfield.
Sizemore, 45, was on probation for a previous drug conviction.
He was arrested in Bakersfield for investigation of seven drug-related charges, including methamphetamine possession.
He has been in jail without bail since June 5, when he surrendered on a warrant alleging he had violated his probation.
Sizemore's screen credits include "Saving Private Ryan" and "Black Hawk Down."