Circle Circumference Calculator
Calculate a circle's circumference from its radius using 2πr.
How to use
- Enter radius r.
- Calculate to obtain circumference 2πr.
Capabilities and scope
The output is the length of one trip around the circular boundary.
How it works
It uses C = 2πr.
Example
A circle with radius 5 has circumference about 31.4159.
Useful for
- Estimate trim or band length around a circle
- Convert a known radius to circumference
Before you use it
- The result uses the same length unit as the radius and does not include fabrication allowance.
Frequently asked questions
Is this the same as πd?
Yes. Since d=2r, 2πr and πd are equivalent.