Circle Area and Circumference Calculator
Enter the radius to get the area and circumference of a circle.
Area78.54
Circumference31.42
How it is calculated
Area = π × r². Circumference = 2 × π × r.
Worked example
| Area | 78.54 |
| Circumference | 31.42 |
FAQ
What if I know the diameter?
Radius = diameter ÷ 2.
Are the results exact?
Results are estimates for information only; check official sources for binding figures.