Enter the radius to get the diameter, circumference and area. Nothing leaves your browser.
Area = π × r². Circumference = 2 × π × r. Diameter = 2 × r. Results are rounded to 4 decimal places.
Multiply π (3.14159…) by the radius squared. A radius of 5 gives about 78.5398.
Multiply 2 × π × radius. A radius of 5 gives about 31.4159.
Divide it by 2 to get the radius, then enter that.
Any. The area is in the square of whatever unit you enter the radius in.
No. Everything is calculated in your browser and nothing is sent or stored.
Free tool, provided as is, with no guarantee. Results are for general information. Please do not enter personal information in feedback.