How it works
A circle’s primary measures share the radius. π links circumference and diameter: π = C/D.
D=2R · C=2πR · A=πR²
When to use
Use this tool when you need to: try R=5, D=10, C=2π (unit circle), or A=25π. Diagram highlights the known measure.
How to use this tool
- Enter your values in the fields above.
- Review the formula and any mode options for your problem.
- Read the result and the step-by-step solution.
Try R=5, D=10, C=2π (unit circle), or A=25π. Diagram highlights the known measure.
Frequently asked questions
- What is the Circle Calculator?
- A circle’s primary measures share the radius. π links circumference and diameter: π = C/D.
- How do I use the Circle Calculator?
- Enter the required values, then calculate. The Circle Calculator shows results, formulas, and step-by-step work when available. No account is required.
- What formula does the Circle Calculator use?
- D=2R · C=2πR · A=πR²
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