Circumference formula The ratio of the circumference to the diameter of any circle is a constant known as pi p which is equal to approximately 314159. To calculate the circumference of a circle use the formula C pd where C is the circumference d is the diameter and p is 314. The diameter of a circle is the length of a straight line drawn between two points on a circle where the line also passes through the centre of a.
Circumference of circle p x Diameter of circle This is typically written as C pd.
It is the ratio of circumference to diameter of any circle. C Circle circumference. You can also use the formula for circumference of a circle using radius which is C 2pr. From this relationship we can derive the formula for the circumference of a circle.