Understanding the numbers
Roof pitchis the rise of the roof over the run of the roof. The rise is the height of the roof, from the base to the top. For example, if a roof is 8 feet high and spreads out from the center covering 12 feet in each direction, the rise over the run would be 8/12.
Consider a right triangle. The bottom, horizontal line of the triangle is the base of the roof. The straight, vertical line runs from the base to the top for total height. This distance is the rise.