The perimeter of a regular octagon is the total length of its outline — the sum of all eight equal sides. It comes up in construction (octagonal window frames), graphic design, and any time you need to know the edge length of an eight-sided shape.

The Formula

P = 8 × t

• P — perimeter of the octagon (cm, m, etc.)
• t — side length (all eight sides are equal)

The perimeter of any regular polygon is simply the number of sides times the length of one side. For an octagon that is eight equal sides, so the calculation is straightforward with no approximations needed.

Step-by-Step Example