Calculate the circumference of a circle using radius or diameter. Get instant results with step-by-step solutions and visual formulas.
Red line: Radius (r)
Green line: Diameter (d = 2r)
Dashed circle: Circumference (C = 2πr)
Circumference is the distance around the edge of a circle - essentially the perimeter of a circle. It represents the total length you would travel if you walked around the circle's boundary.
The formula for circumference is C = 2πr (using radius) or C = πd (using diameter), where C is circumference, π ≈ 3.14159, r is radius, and d is diameter.