Lindsay Lohan will almost certainly get out of jail in a matter of minutes ... this according to officials from the L.A. County Sheriff's Department.
Two Sheriff's Dept. officials tell us ... if someone receives a misdemeanor sentence of 90 days or less, they are routinely processed in and then released. As one of the officials put it, "She'll be out without even having to change her clothes."
Judge Stephanie Sautner sentenced Lindsay to serve 30 days in the pokey, adding that the only way to shave time off the sentence is if it's required by law. A Sheriff's official told us earlier this week ... misdemeanor inmates only serve 20% of the actual sentence because of overcrowding. But the 2 officials we spoke with today say ... because of overcrowding they immediately release inmates sentenced to less than 90 days.
As for what the judge said -- that the sentence can only be reduced if required by law -- the officials say there's a federal court order on overcrowding that "trumps everything," and that order has been interpreted to immediately release people with short jail sentences.
Sheriff's spokesperson Steve Whitmore just confirmed with TMZ ... Lindsay will get in and out of jail pronto, adding the only reason there might be any sort of delay is if there are lots of other inmates who are being processed out at the same time.