Octagon Calculator
Calculate properties of a regular octagon including area, perimeter, and diagonals.
Calculate From
Regular Octagon
--- Apothem--- Circumradius
Area
120.7107
Perimeter
40.0000
Dimensions
Side Length5.0000
Apothem6.0355
Circumradius6.5328
Width (flat to flat)12.0711
Diagonals
Short Diagonal9.2388
Medium Diagonal12.0711
Long Diagonal13.0656
Angles
Interior Angle135
Exterior Angle45
Sum of Interior Angles1080
Octagon Formulas
Area
A = 2(1 + sqrt(2)) * s
Perimeter
P = 8s
Interior Angle
Interior = (n-2)*180/n = 135