How to Figure Wall Length for Octagons

Use an octagonal shape for an impressive backyard gazebo or an unusual room addition for your house. For construction projects, you likely want a regular octagon --- one in which all the sides have the same length. If you know the size of a square area you have to work with, you can calculate the lengths of the sides. After you know the side length, you can also find the perimeter and area of the octagon.

Instructions

1. • 1

     Measure and record the length of one side of the square area into which the octagon should fit. The width and height of the finished octagon will equal this length.

   • 2

     Multiply the length by 0.207. For a 10-foot square, for example, 10 feet times 0.207 equals 2.07 feet.

   • 3

     Multiply the result by 2 to find the length of the octagon's sides. For example, 2.07 feet times 2 equals 4.14 feet for each side.