Last updated on July 29th, 2025
The perimeter of a shape is the total length of its boundary. The sum of all eight sides is called the perimeter of an octagon. Perimeter is also used for fencing a property, sewing, and more. In this topic, we will learn about the perimeter of an octagon.
The perimeter of an octagon is the total length of its eight sides. By adding the length of all eight sides, we get the perimeter of the shape. The formula for the perimeter of a regular octagon is 𝑃 = 8 × 𝑎, where 𝑎 is the length of one side of the octagon. For instance, if an octagon has equal sides each measuring 6 units, then its perimeter is 𝑃 = 8 × 6 = 48 units.
Let’s consider another example of a regular octagon with side lengths, 𝑎 = 10 units. So the perimeter of the octagon will be: 𝑃 = 8 × 𝑎 = 8 × 10 = 80 units.
To find the perimeter of a regular octagon, we just need to apply the given formula and multiply the length of one side by eight. For instance, a regular octagon has sides of length 7 units. Perimeter = 8 × side length = 8 × 7 = 56 units. Example Problem on Perimeter of Octagon - For finding the perimeter of a regular octagon, we use the formula, 𝑃 = 8 × 𝑎. For example, let’s say, each side 𝑎 = 9 cm. Now, the perimeter = 8 × 9 = 72 cm. Therefore, the perimeter of the octagon is 72 cm.
Learning some tips and tricks makes it easier for children to calculate the perimeter of octagons. Here are some tips and tricks given below: Always remember that a regular octagon's perimeter is simply 8 times the length of one side of the shape. For that, use the formula, 𝑃 = 8 × 𝑎. Calculating the perimeter of an irregular octagon starts by determining the length of each side. Then, sum all the side lengths to find the perimeter. To reduce confusion, specifically, arrange the indicated side lengths if you need the perimeter of a group of octagons. After that, apply the appropriate formula to each octagon. To avoid mistakes when adding the perimeter, make sure the side lengths are precise and consistent for common uses like gardening and architecture. If you are given the semi-perimeter, which is half the perimeter, you can multiply it by 2 to determine the full perimeter.
Did you know that while working with the perimeter of an octagon, children might encounter some errors or difficulties? We have many solutions to resolve these problems. Here are some given below:
A regular octagonal-shaped garden has a perimeter of 64 meters and all sides are equal. What is the length of one side of the garden?
Length of one side = 8 meters.
Let ‘a’ be the length of one side. And the given perimeter = 64 meters. Perimeter of regular octagon = 8 × a 64 = 8 × a a = 64 ÷ 8 = 8 Therefore, the length of one side is 8 meters.
A piece of wire with a total length of 160 inches is reshaped into a regular octagon. Find the length of each side of the octagon.
20 inches
Given that the total length of the wire is equal to the perimeter of the octagon, here is the solution: Perimeter of the octagon = Total length of the wire Perimeter of a regular octagon = 8 × a 160 = 8 × a 160 ÷ 8 = 20 a = 20 Therefore, the length of each side of the octagon is 20 inches.
Find the perimeter of a regular octagon whose sides are each 15 cm.
120 cm
Perimeter of octagon = 8 × a P = 8 × 15 = 120 Therefore, the perimeter of the octagon is 120 cm.
Jamie is planning an octagonal flower bed in her backyard. She measures the length of each side of the bed to be 5 meters. How much fencing should Jamie buy to go around the edge of the bed?
Jamie will need 40 meters of fencing to go around the bed.
The perimeter of a regular octagon is the sum of all the eight sides. Using the formula: P = 8 × a P = 8 × 5 = 40 meters.
A stop sign is in the shape of a regular octagon with each side measuring 12 inches. Find the perimeter of the sign.
Perimeter = 8 × 12 = 96 inches.
Each side of the regular octagon is equal. The entire distance around the stop sign is calculated to be 96 inches by multiplying the length of one side by eight.
Perimeter: The total length of the sides of a shape. Octagon: A polygon with eight sides and eight angles. Regular Octagon: An octagon where all sides and angles are equal. Irregular Octagon: An octagon with sides and angles of different lengths and measures. Formula for Perimeter: The mathematical expression used to calculate the perimeter of a regular octagon is 𝑃 = 8 × 𝑎.
Seyed Ali Fathima S a math expert with nearly 5 years of experience as a math teacher. From an engineer to a math teacher, shows her passion for math and teaching. She is a calculator queen, who loves tables and she turns tables to puzzles and songs.
: She has songs for each table which helps her to remember the tables