What is this calculator?
Calculate area, circumference and diameter from radius.
What can you use it for?
Use it when solving an exercise, checking a result, or working with the particular quantities shown in this form. Calculate area, circumference and diameter from radius.
How to use it
- Enter radius.
- Select Calculate (or Generate for random tools).
- Read the answer and any additional results below the form. Check the units and the limits of the method.
Formula and method
Circumference = 2 × pi × radius
Diameter = 2 × radius
The formula uses the units and definitions shown above. Each input is substituted before the arithmetic is evaluated; the calculated output is rounded for display.
Worked example
Radius: 5. The result is 78.53981634 square units (area).
Assumptions and limits
Inputs and outputs must stay within the supported finite number range. Displayed decimal answers may be rounded.
Frequently asked questions
What inputs does the Circle Calculator need?
Use radius. Read the answer and any additional results below the form. Check the units and the limits of the method.
What assumptions apply to the Circle Calculator?
Inputs and outputs must stay within the supported finite number range. Displayed decimal answers may be rounded.