Circumference Formula

The circumference formula of a circle is obtained by multiplying the diameter by pi(π). To recall, the circumference of a closed curve or circular object is the linear distance around its edge. The circumference of a circle has special importance in geometry and trigonometry.

Formula to Calculate Circumference of a Circle

Formula to Calculate Circumference of a Circle

Formula to Find Circumference

The Circumference Formula requires either the radius or the diameter of the circle for its calculation.

Circumference of a Circle C = 2πr = πd


  • C is the circumference of the circle.
  • d is the diameter of the circle.
  • r is the radius of the circle.

Circumference Formula in Terms of Area

C = 2√(πA)

Solved Examples

Question:The radius of a circle is 2 inches. What is the circumference of the circle?



Radius of the circle = r = 2 inches

Circumference of the circle = 2πr = 2 × π × 2 inches = 12.56 in

Practise This Question

Three identical cars A, B and C are moving at the same speed on three bridges. The car A goes on a plane bridge, B on a bridge convex upward and C goes on a bridge concave upward. Let FA,FB and FC  be the normal forces exerted by the cars on the bridges when they are at the middle of bridges.