Circle Circumference Calculator
Going Around the Outside
Unlike area, a circle's circumference scales linearly with its radius — double the radius and the distance around exactly doubles too. That's the same π that shows up in the area formula, just applied to a straight-line multiple rather than a squared one.
The Formula
Circumference = 2πr
Circumference by Radius
| Radius | Circumference |
|---|---|
| 1 | 6.2832 |
| 2 | 12.5664 |
| 3 | 18.8496 |
| 5 | 31.4159 |
| 10 | 62.8319 |
Where This Matters
- Fencing and trim — ordering the right length of edging, rope, or fencing for a circular garden bed or pool.
- Wheel and belt mechanics — the circumference of a wheel is the distance it covers in one full rotation, which drives gear ratio and speed calculations.
- Cylindrical wrapping — figuring the material needed to wrap around a pipe, tank, or column.
How to Use This Calculator
- Enter the circle's Radius.
- Select Calculate to get the circumference.
Related Calculations
Need the enclosed area instead? Use the Circle Area Calculator, or wrap the circle into a cylinder with the Cylinder Volume Calculator.