Radius to Circumference
Convert any radius value to its circumference instantly. Enter the radius below and get the circumference using the formula C = 2πr.
Radius to Circumference Formula
To find the circumference from a known radius, multiply the radius by 2π:
C = 2πr
The circumference C equals 2 times pi times the radius r. 2π is approximately 6.28318.
For example, find the circumference of a circle with a radius of 5:
C = 2π × 5 = 31.4159
The circumference of this circle is 31.4159.
Frequently Asked Questions
Multiply the radius by 2π (6.28318). The formula is C = 2πr. For example, a radius of 5 gives a circumference of 31.4159.
C = 2π × 10 = 62.8318. The circumference is approximately 62.83 units.
Yes, circumference is the specific term for a circle's perimeter — the total distance around the circle. Both terms refer to the same measurement.