How many hours is from 630pm until 8am?

From 6:30 PM to 8:00 AM the next day is a total of 13.5 hours. This is calculated by counting the hours from 6:30 PM to midnight (5.5 hours) and then from midnight to 8:00 AM (8 hours), resulting in 5.5 + 8 = 13.5 hours.