Perimeter is the total distance around the outside of a two-dimensional shape. It is calculated by adding up the lengths of all the sides.

What is the difference between perimeter and area?

Perimeter is the distance around a shape (a one-dimensional measurement), while area is the amount of space inside a shape (a two-dimensional measurement).

What is the perimeter of a circle called?

The perimeter of a circle has a special name: circumference.

Calculate the Perimeter of a Shape

The Perimeter Calculator is a simple tool for finding the distance around a two-dimensional shape. Whether you're working on a math problem, a home improvement project, or just need a quick calculation, our tool can find the perimeter for a variety of common shapes. Just select your shape and enter the required dimensions.

Perimeter Calculator

Calculate the perimeter of various geometric shapes including rectangles, squares, triangles, circles, and polygons. Enter the required dimensions and select your shape to get instant perimeter calculations.

Shape Selection

Select Shape:

Unit:

Length:

Width:

Display Options

Decimal Places:

Show formula

Show calculation steps

About Perimeter

The perimeter is the total distance around the boundary of a two-dimensional shape. It is measured in linear units and represents the length of the outline of any polygon or closed curve.

Common Perimeter Formulas

Rectangle: P = 2(length + width)
Square: P = 4 × side
Triangle: P = side₁ + side₂ + side₃
Circle (Circumference): C = 2πr or C = πd
Parallelogram: P = 2(base + side)
Regular Polygon: P = n × side length

Applications of Perimeter

Understanding perimeter is essential for:

Fencing and boundary calculations for properties
Determining the amount of material needed for borders or frames
Calculating running tracks and race distances
Architectural and construction planning
Landscaping and garden design
Floor planning and room measurements

Tips for Accurate Calculations

Always use the same unit of measurement for all dimensions
For irregular shapes, measure each side carefully
Remember that perimeter is always a linear measurement
Use π ≈ 3.14159 for circular calculations
Double-check measurements before calculating

What Is the Perimeter Calculator?

The Perimeter Calculator is an easy-to-use online tool that helps you quickly find the perimeter of different geometric shapes. It supports rectangles, squares, triangles, circles, trapezoids, parallelograms, ellipses, and regular polygons. By simply entering the measurements of your shape, the calculator instantly provides accurate perimeter values along with the formula and calculation steps. This tool is especially helpful for students, teachers, engineers, and anyone working on design, construction, or measurement tasks.

Formulas Used in the Calculator

Rectangle: \( P = 2(l + w) \)

Square: \( P = 4s \)

Triangle: \( P = a + b + c \)

Circle (Circumference): \( C = 2\pi r \) or \( C = \pi d \)

Parallelogram: \( P = 2(b + s) \)

Trapezoid: \( P = a + b + c + d \)

Regular Polygon: \( P = n \times s \)

Ellipse (Approximation): \( P \approx \pi(a + b)\left(1 + \frac{3h}{10 + \sqrt{4 - 3h}}\right) \), where \( h = \frac{(a - b)^2}{(a + b)^2} \)

How to Use the Perimeter Calculator

Follow these simple steps to use the calculator effectively:

Select the shape: Choose the geometric shape you want to calculate the perimeter for from the drop-down menu.
Enter the dimensions: Input the required measurements such as side lengths, radius, or axes, depending on the shape.
Choose your unit: Select the preferred unit of measurement (cm, m, mm, ft, etc.).
Set decimal places: Decide how many decimal places you want your result rounded to.
Click “Calculate Perimeter”: Instantly view the result, formula, and calculation steps.
Optional display: You can show or hide the formula and detailed calculation steps for clarity.

Why Use This Calculator?

This tool simplifies the process of calculating perimeters, saving you time and reducing the chance of manual error. It provides clear explanations and formulas so you can understand how the result was derived. Whether you’re checking the boundary of a field, designing a frame, or studying geometry, this calculator ensures precision and efficiency.

Benefits and Applications

Perfect for students learning geometry and measurement concepts.
Useful for architects and engineers who need quick boundary calculations.
Helps landscapers and gardeners plan fencing or edging lengths.
Supports DIY projects like room layouts, flooring, or decorative borders.
Includes multiple unit conversions for global usability.

Tips for Accurate Results

Use the same unit for all entered dimensions.
Ensure all sides are measured correctly before entering them.
For circular or curved shapes, use π ≈ 3.14159 for better precision.
Check the “Show formula” option to understand the calculation.
Double-check your input values to avoid rounding errors.

Frequently Asked Questions (FAQ)

1. What is the perimeter?

The perimeter is the total distance around the boundary of a two-dimensional shape. It represents the length of the outline of any closed figure.

2. Can I calculate both metric and imperial units?

Yes. The calculator supports various units including centimeters, meters, inches, feet, yards, and miles. You can easily switch units for instant conversions.

3. Does the calculator show how the answer is calculated?

Absolutely. You can enable the “Show calculation steps” option to see each step of the process, including the formula and substituted values.

4. What if I enter invalid or missing values?

If you leave a field empty or enter an invalid value, the calculator will alert you to correct the input before proceeding.

5. Can this calculator handle complex shapes?

It supports a variety of standard geometric shapes, including polygons and ellipses. For irregular shapes, measure and sum each side manually using the tool’s unit converter.

Conclusion

The Perimeter Calculator offers a straightforward and reliable way to calculate perimeters for educational, practical, or professional use. It combines simplicity with accuracy, helping users make quick and informed measurements. Whether you’re preparing for a project or learning geometry, this calculator makes perimeter calculation clear and effortless.

More Information

Perimeter Formulas:

Square: P = 4s (where 's' is the side length)
Rectangle: P = 2l + 2w (where 'l' is the length and 'w' is the width)
Triangle: P = a + b + c (where 'a', 'b', and 'c' are the side lengths)
Circle (Circumference): C = 2πr (where 'r' is the radius)

The perimeter is the total length of the boundary of a closed shape.

Frequently Asked Questions

What is perimeter?: Perimeter is the total distance around the outside of a two-dimensional shape. It is calculated by adding up the lengths of all the sides.
What is the difference between perimeter and area?: Perimeter is the distance around a shape (a one-dimensional measurement), while area is the amount of space inside a shape (a two-dimensional measurement).
What is the perimeter of a circle called?: The perimeter of a circle has a special name: circumference.

About Us

We create fundamental geometry tools that are easy for everyone to use. Our goal is to provide fast and accurate calculators for common geometric figures, helping students and DIYers with their projects.