Circle Area Calculator
Find the area and circumference of a circle from its radius.
How this calculator works
Area equals pi times the radius squared. Circumference equals two times pi times the radius.
Frequently asked questions
What do I need to enter?
Enter the radius, then select Calculate. The result shows the area and circumference.
Can you show an example?
With radius 5, the area is 78.5398 and the circumference is 31.4159.
How accurate is the result?
The calculator uses the exact formula and only rounds the number it displays, so the answer is as accurate as the values you enter.
