How it works
Calculate circle area, circumference and diameter from the radius. Do not enter the diameter in the radius field.
Inputs and units
| Input | Example value | What to enter |
|---|---|---|
| Radius | 5 | Enter a numeric value. Distance from the centre to the edge; half the diameter. Must be greater than zero. |
Worked example
Show example inputs and results
This example is generated by the same calculation engine using the starting values in the form. Your own inputs produce your own result.
- Radius
- 5
Complete example results
- Area
- 78.53981634
- Circumference
- 31.41592654
- Diameter
- 10
Reading the result
Enter lengths in the same unit. Area uses the square of that unit and volume its cube. Height is perpendicular to the base; use a sloping side only when the input explicitly asks for it.
Questions and answers
Can I use the example values for my own calculation?
The example values illustrate the calculation. Replace every input with your own information, especially dates, rates and the selected operation.
Why are some results rounded?
Results display up to 8 decimal places. Calculations use the unrounded values; very small values use scientific notation. JavaScript floating-point arithmetic can introduce tiny rounding differences.
Are my inputs sent to a server?
The calculator processes inputs in your browser. Its code does not send your values to a server.