The goal post must be a minimum of 20 feet above the crossbar and the crossbar is 10 feet above the ground, so that would make the top of the goal post a minimum of 30 feet above
http://wiki.answers.com/Q/What_is_the_height_of_go...

1. Measure and mark two 10foot pipes at the 4foot mark. Also measure and mark two 10foot pipes at the 2foot mark. 2. Cut the pipes using a saw and then gently sand down the edges
http://www.ehow.com/how_7921633_installfootballg...

Height of goal posts: At least 30 feet. Height of
http://www.chacha.com/question/whatistheheight...

There is only a minimum on the length of the uprights. It is 20 feet above the crossbar. They uprights can into infinity, but 20 feet is the minimum.
http://answers.yahoo.com/question/index?qid=200809...
