## How to calculate the circumference of a circle.

The circumference of a circle can be calculated using the formula:

2 x π x r

Where π (pi) = approx 3.14

and r = the radius

(You can divide the diameter by 2 to find the radius)

## Example

You’ve been asked to calculate the circumference of a circle, you measure the diameter and find it is 2m.

First find the radius

**Radius (r) = Diameter (D) ÷ 2**

**r = 2m ÷ 2 **

**r = 1m**

Then calculate the **circumference** (**C**)

**C = 2 x π x r**

**C = 2 x 3.14 x 1m**

**C = 6.28 x 1m**

**C = 6.28m**

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In the real sense of the world, Engineers normally use Pi X Diameter to calculate the circumference of the circle as it is difficult to measure radius on the field. Consequently the area of a circle is also calculated as pi X (D^2/4). Where D is the diameter.