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Circumference Calculator


What is 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), circumfrence formula to calculate circumference will be

$$ \bbox[#f6f6f6,10px]{C\;=\;2r}$$

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

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

$$ \bbox[#f6f6f6,10px]{C\;=\;d}$$

What is Circumference formula?

The distance around a circle is known as the circumference. The circumference formula is

$$ \bbox[#f6f6f6,10px]{C\;=\;2πr}$$

Concept of circumference is different from area of a sector. To learn about area of a sector and to calculate its equations, try Area Of A Sector Calculator. You will also learn how to find diameter from circumference by using circumference of a circle calculator.

What is Radius?

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

$$ \bbox[#f6f6f6,10px]{r\;=\;\frac{d}{2}}$$

Or you can calculate radius from circumference too by using this formula. Radius calculator uses the same formula as well

$$ \bbox[#f6f6f6,10px]{r\;=\;\frac{C}{(*2)}}$$

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

$$ \bbox[#f6f6f6,10px]{r\;=\;\frac{C}{(*2)}}$$ $$\bbox[#f6f6f6,10px]{r=\frac{20}{(3.14*2)}=3.18cm}$$

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

Radius also deals with pythagorean theorem. To learn about hypotenuse, x and y coordinates, circles & triangles, try Pythagorean Theorem Calculator for free.

What is 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.

$$ \bbox[#f6f6f6,10px]{d = 2 * r}$$

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

$$ \bbox[#f6f6f6,10px]{d\;=\;\frac{c}{π}}$$

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. It is also used to calculate rectangle area. To calculate radius of a rectangle, use Rectangle Area Calculator. You can use our circumference calculator as circumference to diameter calculator.

What is 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.

$$ \bbox[#f6f6f6,10px]{π=\frac{C}{d}}$$

How to calculate 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.

How to Calculate the Circumference of a Circle

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.

How to calculate Circumference with Circumference formula?

To avoid manual calculations one can use circumference formula calculator to get equation for circumference solved quickly, For manual calculations, process is below mentioned.

Circumference formula

Circumference of circle = 2πr

While π = 3.14

By putting values C = 2 * 3.14 * 3.5


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 calculator

$$\bbox[#f6f6f6,10px]{Circumference\;=\;πd\;\;}$$ $$\bbox[#f6f6f6,10px]{d\;=\;diameter}$$

By putting value C = 3.14 * 7


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


Circumference problem

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





By putting the values into formula

$$\bbox[#f6f6f6,10px]{C\;=\;3.14 * 40}$$ $$\bbox[#f6f6f6,10px]{C\;=\;126 cm}$$

While 1km = 100,000

Number of complete rotation = 100,000 / 126


Circumference to Diameter Calculator

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,



This equation of diameter to circumference is also a definition of the constant. It is also used in finding cone volume. To learn about what is cone volume and how can we calculate it, use Cone Volume Calculator.

How to calculate Circumference with 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.

You can try our CBM Calculator to calculate triangles, cubic feet from length and width.

We hope you liked our circumference calculator which calculate circumference accurately. Please provide us your feedback. Cheers!

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Average user rating

5 / 5

amir shahzad
it works fine. thank you for helping