Perimeter of a Circle Calculator


What is the Perimeter of a Circle?

The perimeter of a circle, also called the circumference, is the total distance around the boundary of the circle. If you walk along the edge of a circular object, the distance you travel is its perimeter.

This is a fundamental concept in geometry and has applications in real-world scenarios such as construction, engineering, and measurement.

Formula to Calculate the Perimeter (Circumference)

There are two common formulas depending on the known input:

  • Using Radius (r): Perimeter = 2 × π × r
  • Using Diameter (d): Perimeter = π × d

Where π (pi) ≈ 3.1416, r is the radius, and d is the diameter (2 × radius).

Diagram

r Perimeter = 2πr

Examples

Example 1: Using Radius

Question: What is the perimeter of a circle with a radius of 7 cm?

Solution:

Perimeter = 2 × π × r
          = 2 × 3.1416 × 7
          ≈ 43.982 cm

Answer: The perimeter is approximately 43.98 cm.

Example 2: Using Diameter

Question: What is the perimeter of a circle with a diameter of 10 meters?

Solution:

        Perimeter = π × d
          = 3.1416 × 10
          ≈ 31.416 m

Answer: The perimeter is approximately 31.42 meters.

How to Use the Perimeter of a Circle Calculator

The Perimeter of a Circle Calculator provided on this page allows you to quickly calculate the perimeter by entering either the radius or the diameter. Here’s how:

  1. Select the input type: Radius or Diameter
  2. Enter the value into the input field
  3. Click the Calculate button
  4. The perimeter will be displayed instantly

This tool is perfect for students, professionals, and anyone working with circular measurements.

Try It Now

Use the Perimeter of a Circle Calculator below. Enter a value and let the calculator do the rest!