BrightChamps Logo
Login
Creative Math Ideas Image
Live Math Learners Count Icon104 Learners

Last updated on August 5th, 2025

Math Whiteboard Illustration

Area Of Octagon Calculator

Professor Greenline Explaining Math Concepts

A calculator is a tool designed to perform both basic arithmetic operations and advanced calculations, such as those involving geometry. It is especially helpful for completing mathematical school projects or exploring complex mathematical concepts. In this topic, we will discuss the Area Of Octagon Calculator.

Area Of Octagon Calculator for Filipino Students
Professor Greenline from BrightChamps

What is the Area Of Octagon Calculator

The Area Of Octagon Calculator is a tool designed for calculating the area of an octagon.

 

An octagon is a two-dimensional shape with eight sides.

 

Each side of a regular octagon is equal in length, and all interior angles are equal.

 

The term "octagon" comes from the Greek word "okta," meaning "eight," and "gonia," meaning "angle."

Professor Greenline from BrightChamps

How to Use the Area Of Octagon Calculator

For calculating the area of an octagon using the calculator, we need to follow the steps below -

 

Step 1: Input: Enter the side length

 

Step 2: Click: Calculate Area. By doing so, the side length we have given as input will be processed

 

Step 3: You will see the area of the octagon in the output column

Professor Greenline from BrightChamps

Tips and Tricks for Using the Area Of Octagon Calculator

Mentioned below are some tips to help you get the right answer using the Area Of Octagon Calculator.

 

Know the formula: The formula for the area of a regular octagon is (2(1+√{2})s2), where ‘s’ is the side length.

 

Use the Right Units: Make sure the side length is in the right units, like centimeters or meters.

 

The answer will be in square units (like square centimeters or square meters), so it’s important to match them.

 

Enter Correct Numbers: When entering the side length, make sure the numbers are accurate.

 

Small mistakes can lead to big differences, especially with larger numbers.

Max Pointing Out Common Math Mistakes

Common Mistakes and How to Avoid Them When Using the Area Of Octagon Calculator

Calculators mostly help us with quick solutions.

 

For calculating complex math questions, students must know the intricate features of a calculator.

 

Given below are some common mistakes and solutions to tackle these mistakes.

Mistake 1

Red Cross Icon Indicating Mistakes to Avoid in This Math Topic

Rounding off too soon

Green Checkmark Icon Indicating Correct Solutions in This Math Topic

Rounding the decimal number too soon can lead to wrong results.

 

For example, if the area is 45.67 cm², don’t round it to 46 right away.

 

Finish the calculation first.

Mistake 2

Red Cross Icon Indicating Mistakes to Avoid in This Math Topic

Entering the wrong number as the side length

Green Checkmark Icon Indicating Correct Solutions in This Math Topic

Make sure to double-check the number you are going to enter as the side length.

 

If you enter the side length as ‘5’ instead of 6, the result will be incorrect.

Mistake 3

Red Cross Icon Indicating Mistakes to Avoid in This Math Topic

Mixing up the area formula with the perimeter formula

Green Checkmark Icon Indicating Correct Solutions in This Math Topic

The perimeter of an octagon is calculated as '8s', whereas the area uses '2(1+√{2})s2'.

 

Using the wrong formula will give the wrong result.

Mistake 4

Red Cross Icon Indicating Mistakes to Avoid in This Math Topic

Relying too much on the calculator

Green Checkmark Icon Indicating Correct Solutions in This Math Topic

The calculator gives an estimate.

 

Real objects may not be perfect, so the answer might be slightly different.

 

Keep in mind that it's an approximation.

Mistake 5

Red Cross Icon Indicating Mistakes to Avoid in This Math Topic

Mixing up the positive and negative signs

Green Checkmark Icon Indicating Correct Solutions in This Math Topic

Always check that you’ve entered the correct positive (+) or negative (–) signs.

 

A small mistake, like using the wrong sign for the side length, can completely change the result.

 

Make sure the signs are correct before finishing your calculation.

 

For example, if the side length is 10 cm, entering -10 cm instead of +10 cm could give you an incorrect area.

arrow-right
Max from BrightChamps Saying "Hey"
Hey!

Area Of Octagon Calculator Examples

Ray, the Character from BrightChamps Explaining Math Concepts
Max, the Girl Character from BrightChamps

Problem 1

Help Emma find the area of a regular octagonal garden if each side is 7 m.

Ray, the Boy Character from BrightChamps Saying "Let’s Begin"
Okay, lets begin

We find the area of the garden to be approximately 169.71 m²

Explanation

To find the area, we use the formula: Area = \(2(1+\√{2})s2\)

 

Here, the value of ‘s’ is given as 7

 

Now, we substitute the value of ‘s’ in the formula: Area = \(2(1+\√{2}) \times (7)2\) ≈ 169.71 m²

Max from BrightChamps Praising Clear Math Explanations
Well explained 👍
Max, the Girl Character from BrightChamps

Problem 2

The side length ‘s’ of a stop sign is 9 cm. What will be its area?

Ray, the Boy Character from BrightChamps Saying "Let’s Begin"
Okay, lets begin

The area is approximately 392.52 cm²

Explanation

To find the area, we use the formula: Area = \(2(1+\√{2})s2\)

 

Since the side length is given as 9, we can find the area as Area = \(2(1+\√{2}) \times (9)2\) ≈ 392.52 cm²

Max from BrightChamps Praising Clear Math Explanations
Well explained 👍
Max, the Girl Character from BrightChamps

Problem 3

Find the area of a square with side length ‘s’ as 8 cm and the area of an octagon with side length 4 cm. After finding the area of the square and octagon, take their sum.

Ray, the Boy Character from BrightChamps Saying "Let’s Begin"
Okay, lets begin

We will get the sum as approximately 148.96 cm²

Explanation

For the area of a square, we use the formula ‘A = s2’, and for the octagon, we use ‘A = 2(1+\√{2})s2’.

 

Area of square = \(s2 = 82 = 64\) cm²

 

Area of octagon = \(2(1+\√{2}) \times (4)2\) ≈ 84.96 cm²

 

The sum of areas = area of square + area of octagon = 64 + 84.96 ≈ 148.96 cm²

Max from BrightChamps Praising Clear Math Explanations
Well explained 👍
Max, the Girl Character from BrightChamps

Problem 4

The side length of a decorative octagonal mirror is 12 cm. Find its area.

Ray, the Boy Character from BrightChamps Saying "Let’s Begin"
Okay, lets begin

We find the area of the decorative octagonal mirror to be approximately 695.69 cm²

Explanation

Area = \(2(1+\√{2})s2\) = \(2(1+\√{2}) \times (12)2\) ≈ 695.69 cm²

Max from BrightChamps Praising Clear Math Explanations
Well explained 👍
Max, the Girl Character from BrightChamps

Problem 5

Olivia wants to design an octagonal table top. If the side length of the table top is 15 cm, help Olivia find its area.

Ray, the Boy Character from BrightChamps Saying "Let’s Begin"
Okay, lets begin

The area of the octagonal table top is approximately 1308.29 cm²

Explanation

Area of octagonal table top = \(2(1+\√{2})s2\) = \(2(1+√{2}) \times (15)2\) ≈ 1308.29 cm²

Max from BrightChamps Praising Clear Math Explanations
Well explained 👍
Ray Thinking Deeply About Math Problems

FAQs on Using the Area Of Octagon Calculator

1.What is the area of the octagon?

The area of the octagon uses the formula \(2(1+\√{2})s2\), where ‘s’ is the side length.

Math FAQ Answers Dropdown Arrow

2.What is the value of ‘s’ that gets entered as ‘0’?

The side length should always be a positive number.

 

If we enter ‘0’ as the side length, then the calculator will show the result as invalid.

 

The length of the side can’t be 0.

Math FAQ Answers Dropdown Arrow

3.What will be the area of the octagon if the side length is given as 5?

Applying the value of the side length as 5 in the formula, we get the area of the octagon as approximately 120.71 cm².

Math FAQ Answers Dropdown Arrow

4.What units are used to represent the area?

For representing the area, the units mostly used are square meters (m²) and square centimeters (cm²).

Math FAQ Answers Dropdown Arrow

5.Can we use this calculator to find the area of an irregular octagon?

No, this calculator is specifically for regular octagons with equal sides and angles.

 

The area of an irregular octagon requires different methods.

Math FAQ Answers Dropdown Arrow
Professor Greenline from BrightChamps

Important Glossary for the Area Of Octagon Calculator

  • Area: It is the amount of space occupied by a two-dimensional shape.

                     It is measured in square meters (m²) or square centimeters (cm²).

 

  • Side Length: The length of one side of a polygon. For example, in \(2(1+\√{2}) \times 72\), ‘7’ is the side length.

 

  • Regular Octagon: An eight-sided polygon with equal side lengths and equal interior angles.

 

  • Square Units: Units used to measure area, such as m² and cm².

 

  • Pi (π): A mathematical constant representing the ratio of a circle's circumference to its diameter, approximately 3.14159, but not used in the octagon area formula.
Math Teacher Background Image
Math Teacher Image

Seyed Ali Fathima S

About the Author

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.

Max, the Girl Character from BrightChamps

Fun Fact

: She has songs for each table which helps her to remember the tables

INDONESIA - Axa Tower 45th floor, JL prof. Dr Satrio Kav. 18, Kel. Karet Kuningan, Kec. Setiabudi, Kota Adm. Jakarta Selatan, Prov. DKI Jakarta
INDIA - H.No. 8-2-699/1, SyNo. 346, Rd No. 12, Banjara Hills, Hyderabad, Telangana - 500034
SINGAPORE - 60 Paya Lebar Road #05-16, Paya Lebar Square, Singapore (409051)
USA - 251, Little Falls Drive, Wilmington, Delaware 19808
VIETNAM (Office 1) - Hung Vuong Building, 670 Ba Thang Hai, ward 14, district 10, Ho Chi Minh City
VIETNAM (Office 2) - 143 Nguyễn Thị Thập, Khu đô thị Him Lam, Quận 7, Thành phố Hồ Chí Minh 700000, Vietnam
UAE - BrightChamps, 8W building 5th Floor, DAFZ, Dubai, United Arab Emirates
UK - Ground floor, Redwood House, Brotherswood Court, Almondsbury Business Park, Bristol, BS32 4QW, United Kingdom