Perimeter of a Polygon Calculator

To calculate the perimeter of a regular polygon, simply multiply the number of sides n times the side length a:

perimeter = n × a

If you want to determine the perimeter of any polygon, sum the lengths of all its sides:

• perimeter = Σ aᵢ

  where a₁, a₂, ..., a_n are consecutive sides lengths

  Σ is the sum symbol (from i = 1 to n)

Or use the vertices coordinates:

• perimeter = Σ√[(xᵢ₊₁ - xᵢ)² + (yᵢ₊₁ - yᵢ)²]

  with x(n+1) → x(1) and y(n+1) → y(1)

Have a look at this easy example:

1. Pick the polygon type. Suppose we want to calculate the perimeter of an octagon shape.

2. Type the number of sides. We've chosen the other... option, so we need to manually enter the number of sides. It's 8.

3. Enter the side length. Assume it's 17 in.

4. Voilà! The perimeter of a polygon calculator shows the result. The perimeter of such an octagon is equal to 136 in.

Now that you know how to find the perimeter of a polygon, are you curious about how to calculate its area? Then check out our area of a regular polygon calculator.
Maybe you're interested in calculating the perimeter of a circle instead of a polygon? Then our circle perimeter calculator is what you need.