Circle Calculator
Radius, diameter, circumference, and area. Enter any one; the rest follow with π from this device.
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How to use Circle Calculator
- Choose known first so the fields that apply to that job appear.
- Enter radius, diameter, circumference. Leave a field blank only when the page says the value is missing.
- Read the result rows under the form. Errors appear in the status line. Nothing is uploaded.
- Rounding follows IEEE floating point in this browser unless the page says it uses integers or BigInt.
Circle Calculator
Any one input
| Computes | Radius, diameter, circumference, and area. Enter any one; the rest follow with π from this device. |
|---|---|
| Includes | Any one input |
| Includes | Circumference and area |
| Engine | geometry |
| Upload | None |
| Advice | Arithmetic only |
What Circle Calculator is
C = 2πr, A = πr², d = 2r. Solving from area uses r = √(A/π). π is the IEEE value in this browser.
The formula runs in this tab. CZNull does not receive the numbers.
How this page computes
Spheres use 4/3 πr³ on the sphere page. Cylinders add height.
Entities and related jobs
Radius, diameter, circumference, and area. Enter any one; the rest follow with π from this device. Named features: Any one input, Circumference and area.
See also Sphere Calculator, Cylinder Calculator, Triangle Calculator, Pythagorean Theorem Calculator, Rectangle Calculator.
Use cases
Pipes, pizza, and running tracks. This is plane geometry, not a CAD fillet.
Limits
Invalid input appears in the status line. IEEE floating point applies unless a row says otherwise. CZNull does not receive the numbers.