The perimeter of a regular decagon is the total length of all its sides added together. Because a decagon has ten equal sides, it has a longer perimeter than any other regular polygon with fewer sides at the same side length.

The Formula

P = 10 × t

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

The perimeter of any regular polygon is the number of sides multiplied by the length of one side. For a decagon with ten equal sides, just multiply the side by 10.

Step-by-Step Example