Circumference calculator

The following circumference calculator is easy to use. Just enter the value of the radius and hit calculate button.


Recall that the formula to get the circumference of a circle  

is 2 ×pi×r with pi = 3.141592653589793

Therefore, the circumference depends only on the size of r. That is why you only need to enter r here to get the circumference.

The calculator will only accept positive value for r since a distance cannot be negative.

As a reminder, if r = 4 cm for instance,

circumference = 2 ×3.14 ×4 = 25.12 cm