Use this simple tool to accurately calculate how many degrees are in any roof pitch, stair stringer, or any other slope standard or metric. Enter the values for the roof pitch in inches per foot rise. Then select a fraction if there is any.
For example: A 12/12 roof pitch would be selected as 12 inches of rise per foot with no fraction and the value generated by the calculator would be 45º. Strangely enough, if a pitch of 6 inches rise per foot is entered, then the degrees generated is not 22.5º, it is 26.6º. Furthermore, if a pitch of 3 inches rise per foot is selected, then the answer returned is 14º. It just doesn’t work that way. It takes three steps using trigonometric functions to achieve an accurate result.
For all other slopes a run must be entered. The box has a pre-defined value of 12 because rafter pitches are the primary function of this calculator. Simply click in the field inside the box and enter a value for the inches and fraction if necessary. For the complementary angle, reverse the rise and run.
The inches box will also accept decimal values making it possible to calculate the degrees for any slope!
For a quick reference for getting the angle of a pitch, use a speed square. Simply line up the common slope with any straight edge and see what degree it is on.