# Circumference Calculator

## Introduction of Circumference Calculator

Whenever you do your craftwork or put fencing around hot tub, or solve mathematical problems in school just to know “How to calculate the circumference of any circle-shaped thing?”, circumference calculator will provide you help to solve your problem in an easy way

To calculate the circumference of a circle, just provide radius to our circumference calculator and get your answer. It will give you area of circle immediately.

Here we are going to discuss some important distances of a circle which are; circumference, radius and diameter. These all calculations have a real importance in our routine life. So let’s know what these are and how can be calculated.

## What are Radius, Pi, Diameter, and Circumference?

There are some properties of circle. Some of them we will discuss here are called; radius, diameter, pi, and circumference.

The radius is half the distance of a diameter denoted by (r).

$$r = d / 2$$

Or you can calculate radius from circumference too by using this formula.

$$r = C / (*2)$$

Suppose the circumference of a circle is 20cm, you want to find the radius. Put the value into the equation.

$$r = C / (*2)$$

$$r = 20 / (3.14 * 2) = 3.18 cm$$

By following this way a radius calculator works to find out the radius of a circle.

### Diameter

The diameter is the distance across the center of a circle denoted by (d).

If you know the radius of a circle, you can calculate the diameter by multiplying the radius by 2.

$$d = 2 * r$$

If you don’t know the radius, you can calculate diameter by dividing the circumference by pi.

$$d = c / π$$

If you don’t know circumference or radius of a circle, you can find the diameter by dividing the area by pi and after that find the square root of that number to get the radius.

Diameter calculator works according to the above-given formula.

### Pi

Pi is the ratio of circumference to its diameter of a circle. The value of this ratio is 3.14156. This value is true for all circles.

$$Pi = C / d$$

### Circumference

The circumference is the distance around the outside of the circle denoted by (C). It is also called the perimeter of the circle.

If you know the value of (r), formula to calculate circumference will be

$$C = 2 r$$

As we know the value of pi is fixed for all circles.

If you know the value of (d), the formula will be

$$C = d$$

There is an odometer used to measure the distance a wheel travels just by the number of wheel revolutions. And you can get an estimate of the age of a tree by measuring the circumference of the tree. Each 2cm of its circumference represent 1-year growth. This formula will be true for many kinds of trees.

## How to Calculate the Circumference of a Circle?

Assume we draw a circle of radius 3.5 centimeters. It will look something like this. As we know this blue boundary of the circle will be its perimeter. The perimeter of the circle is also called circumference.

But how can we measure the circumference of the circle? The circumference is round and the scale is used to measure any straight length. It is very simple. Have a look at given below method.
Find the circumference of the above-given circle, the radius is 3.5 cm.

### Circumference formula:

$$Circumference of circle = 2 πr$$

While π = 3.14

By putting values C = 2 * 3.14 * 3.5

$$C = 22cm$$

So, in this case, when we are given the radius, we can calculate circumference by above-given circumference formula. But if there is given diameter, the circumference formula will be:

$$Circumference = πd$$

$$d = diameter$$

By putting value C = 3.14 * 7

$$C = 22cm$$

As we can get circumference from diameter, likewise, we can find diameter if we are known circumference.

### Example

Circumference problem

The diameter of a wheel is 40 cm. How many complete rotations will denote the distance of 1km?

As

$$C = d$$

While

$$π=3.14$$

By putting the values into formula

$$C = 3.14 * 40$$

$$= 126 cm$$

While 1km = 100,000

Number of complete rotation = 100,000 / 126

$$= 794km$$

## Circumference to Diameter

As you might have noticed that the diameter is 2 times longer than the radius, and the circumference and diameter is dependent on each other in a circle. So,

$$C/D=2πr/2r=π$$

This equation is also a definition of the constant . It uses in many areas of life; mathematics and physics e.g. to find the centrifugal force.
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