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Math Calculators ▶ Circumference Calculator

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An online circumference calculator that allows you to find circumference, radius, diameter, area, sphere surface area, and sphere volume of a circle. This circumference of a circle calculator is 100% free and provides you with precise measurements.

**“It is the distance around the outside of the circle”**

Our calculator utilizes the following circumference of a circle formula:

**C = 2πr**

Where

**r = Radius of the circle **

**π = 3.14159…**

If you find any difficulty in calculations, simply add the values into the above-given circumference formula calculator to calculate circumference. It directly uses the same equation for circumference calculations.

Also, there is another geometry calculator that works best to determine the coordinates of the midpoint with the x & y coordinates.

If the diameter of a circle is 18cm, then how to find the circumference?

As the diameter is as follows:

**D = 18cm**

**As D= 2r**

**r = D/2 = 18/2 = 9cm**

Now we have:

**C = 2πr**

**C = 2 * 3.14 * 9**

**C = 56.52 cm**

A radius of circle is referred to as a straight line from the center of a circle to the circumference of a circle.

As we know that:

**C = 2πr**

Rearranging the above equation to get the radius formula as follows:

**r = C/2π**

If the diameter is given:

**Radius = D/2**

If the area is given:

**Radius = √ A / π**

The circumference calculator also determines the radius along with the circumference with 100% accuracy.

“It is the measure of length from one point on the circumference to another one through the center of the circle”

As we know:

If the circumference is given:

**Diameter = C / π**

If the radius is given:

**Diameter = 2R**

If the area is given:

**Diameter = √4A / π**

Apart from these formulas, you simply add the value into the designated field of the diameter of a circle calculator to find the diameter of the circle instantly.

The above diameter to circumference calculator will directly turn values from diameter to the equivalent circumference value. And, if you want to do it yourself, then swipe down!

**C/d = π**

**C = π x d**

**C = πd**

**C = πd**

**C/π = d**

This calculator for circle circumference is packed with a simple & user-friendly interface through which you can easily find the circumference, area, and different other parameters of a circle.

**Input:**

- Just enter any single parameter value in its field and tap Calculate to get results

**Output:**

- Radius & Diameter
- Circumference
- Area & Sphere Surface Area
- Sphere Volume

From the source of Wikipedia: About Circumference – The term of circle and (relationship with π)

From the source of tutors: about Pi and Circumference/Diameter – Also, Blame Welsh mathematician William Jones used the Greek word for circumference, περιϕέρεια, (π)

From the source of khanacademy: the guide about the relationship between the radius, diameter, and circumference of the circle.

Other Languages: Calculadora Circunferência, Obwód Koła Kalkulator, Kalkulator Keliling Lingkaran, Kreisumfang Rechner, 円周 計算, Výpočet Obvodu, Calcul Circonférence Cercle, Calcolo Circonferenza Cerchio, Длина Окружности Калькулятор.