Octagon Calculator
Results
Area
-
Perimeter
-
Apothem
-
Circumradius
-
Long Diagonal
-
Short Diagonal
-
About Regular Octagon
A regular octagon is an eight-sided polygon where all sides are equal in length and all angles are equal (135°).
Formulas
Area = 2(1 + √2)s²
Perimeter = 8s
Apothem = s(1 + √2)/2
Circumradius = s√(1 + √2)
Long Diagonal = s√(4 + 2√2)
Short Diagonal = s(1 + √2)
Where s is the side length.
Properties
- All sides are equal in length
- All interior angles are 135°
- All exterior angles are 45°
- Has 20 diagonals
- Can be inscribed in a circle