109 LearnersLast updated on August 5th, 2025
Perimeter Of A Rectangle Calculator
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 Perimeter Of A Rectangle Calculator.
What is the Perimeter Of A Rectangle Calculator
The Perimeter of A Rectangle Calculator is a tool designed for calculating the perimeter of a rectangle.
A rectangle is a two-dimensional shape with opposite sides that are equal and parallel.
The perimeter of a rectangle is the total distance around the outside of the rectangle.
It is calculated by adding together twice the length and twice the width of the rectangle.
How to Use the Perimeter Of A Rectangle Calculator
For calculating the perimeter of a rectangle using the calculator, we need to follow the steps below -
Step 1: Input: Enter the length and width.
Step 2: Click: Calculate Perimeter. By doing so, the values given as input will get processed.
Step 3: You will see the perimeter of the rectangle in the output column.
Tips and Tricks for Using the Perimeter Of A Rectangle Calculator
Mentioned below are some tips to help you get the right answer using the Perimeter of A Rectangle Calculator.
Know the formula: The formula for the perimeter of a rectangle is ‘2(l + w)’, where ‘l’ is the length and ‘w’ is the width.
Use the Right Units: Make sure the length and width are in the right units, like centimeters or meters.
The answer will be in linear units (like centimeters or meters), so it’s important to match them.
Enter correct Numbers: When entering the length and width, make sure the numbers are accurate.
Small mistakes can lead to big differences, especially with larger numbers.
Common Mistakes and How to Avoid Them When Using the Perimeter Of A Rectangle 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
Rounding off too soon
Rounding the decimal number too soon can lead to wrong results.
For example, if the perimeter is 31.67 cm, don’t round it to 32 right away.
Finish the calculation first.
Mistake 2
Entering the wrong number as the length or width
Make sure to double-check the numbers you are going to enter as the length and width.
If you enter the length as ‘8’ instead of 9, the result will be incorrect.
Mistake 3
Mixing up 2(l + w) with l × w
‘l × w’ defines the area, whereas ‘2(l + w)’ defines the perimeter of the rectangle.
Using the wrong formula will give the wrong result.
The perimeter of the rectangle is 2(l + w) not l × w.
Mistake 4
Relying too much on the calculator.
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
Mixing up the positive and negative signs
Always check that you’ve entered the correct positive (+) or negative (–) signs.
A small mistake, like using the wrong sign for the length or width, can completely change the result.
Make sure the signs are correct before finishing your calculation.
For example, if the length is 25 cm, entering -25 cm instead of +25 cm could give you an incorrect perimeter.
Perimeter Of A Rectangle Calculator Examples
Problem 1
Help William find the perimeter of a garden if its length is 15 m and width is 10 m.
We find the perimeter of the garden to be 50 m.
Explanation
To find the perimeter, we use the formula: P = 2(l + w)
Here, the value of ‘l’ is given as 15 and ‘w’ is given as 10.
Now, we have to substitute the values of ‘l’ and ‘w’ in the formula: P = 2(l + w) = 2(15 + 10) = 2 × 25 = 50 m.
Problem 2
The length ‘l’ of a rectangular table is 20 cm, and the width ‘w’ is 12 cm. What will be its perimeter?
The perimeter is 64 cm.
Explanation
To find the perimeter, we use the formula: P = 2(l + w)
Since the length is given as 20 and the width is given as 12,
we can find the perimeter as P = 2(l + w) = 2(20 + 12) = 2 × 32 = 64 cm.
Problem 3
Find the perimeter of a rectangle with a length of 8 cm and a width of 5 cm. After finding the perimeter, calculate the area of the same rectangle.
We will get the perimeter as 26 cm and the area as 40 cm².
Explanation
For the perimeter of a rectangle, we use the formula ‘P = 2(l + w)’, and for the area,
we use ‘A = l × w’.
Perimeter of the rectangle = 2(l + w) = 2(8 + 5) = 2 × 13 = 26 cm.
Area of the rectangle = l × w = 8 × 5 = 40 cm².
Problem 4
The length of a swimming pool is 30 m, and the width is 15 m. Find its perimeter.
We find the perimeter of the swimming pool to be 90 m.
Explanation
Perimeter = 2(l + w) = 2(30 + 15) = 2 × 45 = 90 m.
Problem 5
John wants to fence his rectangular backyard. If the length of the backyard is 50 m and the width is 20 m, help John find the perimeter.
The perimeter of the backyard is 140 m.
Explanation
Perimeter of the backyard = 2(l + w) = 2(50 + 20) = 2 × 70 = 140 m.
FAQs on Using the Perimeter Of A Rectangle Calculator
1.What is the perimeter of a rectangle?
2.What if the length or width is entered as ‘0’?
3.What will be the perimeter of a rectangle if the length is 5 and the width is 3?
4.What units are used to represent the perimeter?
5.Can we use this calculator to find the area of a rectangle?
Important Glossary for the Perimeter Of A Rectangle Calculator
- Perimeter: It is the total distance around the outside of a shape.
It is measured in linear units like meters (m) or centimeters (cm).
- Length: One of the longer sides of a rectangle.
- Width: One of the shorter sides of a rectangle.
- Linear Units: Units used to measure length or distance, such as meters (m) and centimeters (cm).
- Formula: A mathematical rule expressed in symbols.
For example, the perimeter of a rectangle is calculated using the formula P = 2(l + w).
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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.
Fun Fact
: She has songs for each table which helps her to remember the tables
