There are many different ways to calculate the angle of a staircase's railing, but the most straightforward method involves the use of two simple measurements. Once these measurements have been made, they can be put into a mathematical formula to determine the angle of the staircase. Since the angle of the staircase and the angle of the staircase's railing should be identical, knowledge of one means that you have knowledge of the other as well.
Measure the vertical distance from the top of the staircase's top step to the top of the staircase's bottom step. The measurements can be made in either inches or centimetres as long as you use the same unit of measurement consistently throughout the process.
Measure the diagonal distance from the tip of the top step to the tip of the bottom step. This is most commonly referred to as the "run" of the staircase. The tip of the step is considered to be the edge along the step where the vertical and horizontal plane of each step meets.
Open you Web broswer and navigate to the Virginia Railing and Gate staircase angle calculator (see Resources).
Insert the measurements from steps one and two into the appropriate blank text fields on the Web page that appears.
Click the calculate button.
For additional accuracy you may consider using a level when taking the measurements.