Octagon Calculator

Area

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Perimeter

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Short Diagonal

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Long Diagonal

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Understanding Octagons

An octagon is a polygon with eight sides and eight angles. A regular octagon has:

  • Eight equal sides
  • Eight equal angles of 135°
  • Eight lines of symmetry

Key Formulas

Area: A = 2(1 + √2)a²

Perimeter: P = 8a

Short Diagonal: s = a√(2 + √2)

Long Diagonal: d = a√(4 + 2√2)