A great question for the less-versed golfers of the world, how is par determined? Well, according to Richard Fellner, editor of Inside Golf Magazine, the USGA defines par as, "The score that an expert player would be expected to make for a given hole. Par means expert play under ordinary weather conditions, allowing two strokes on the putting green."
Looking to the USGA again, Fellner says, a scratch male golfer can "hit tee shots an average of 250 yards and reach a 470-yard hole in two shots at sea level. A female scratch golfer can hit tee shots an average of 210 yards and can reach a 400-yard hole in two shots at sea level."
Therefore any hole 250 yards or less is considered par-3, whereas holes up to 470 yards are generally considered par-4, and holes over 470 yards are generally par-5. While this can vary depending on the handicap of the players, this is the general rule for deciding par for each hole on a course.
For the entire answer from the man himself, check out the article at sportingnews.com below.