Answer:
If you're asking how far apart are the two uprights on a single goal post, they are 18 feet 6 inches apart in college and pro, and 23 feet 4 inches apart in high school.
If you're asking how far apart is one team's goal post from the other team's goal post on the opposite end of the field, they are 120 yards apart. (10 yards for each end zone and 100 yards for the length of the field in-between.)