It varies from command to command, and it also depends alot on the conditions you went AWOL under. I worked in a military prison for 2 years, so I've seen quite a few cases. In some instances, like trainees walking away from Basic, they serve 30 days in jail, then go back to be administratively separated from the Army. In other cases it's more severe, for instance; an active duty E-5 whose unit was about to deploy to Iraq went AWOL. He received an 18 month sentence due to the circumstances.