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Circle Calculator
Area, circumference, radius and diameter.
78.539816
Area
31.415927
Circumference
5
Radius
10
Diameter
Runs entirely in your browser. Nothing is sent anywhere.
How it works
- 1Enter your values.
- 2See the result update instantly as you type.
- 3Change any value to compare scenarios.
About this tool
Circle Calculator: Area, circumference, radius and diameter. Type your numbers and the result is calculated instantly — no button to press, nothing to install. All math runs locally in your browser, so the values you enter are never sent anywhere.
Example
| Input | |
|---|---|
| Value | 5 |
| Given | Radius |
| Result | |
| Area | 78.539816 |
| Circumference | 31.415927 |
| Radius | 5 |
| Diameter | 10 |
How do I use the Circle Calculator?
Enter your values. See the result update instantly as you type. Change any value to compare scenarios.
Is the Circle Calculator free?
Yes. It is completely free with no sign-up, no usage limits and no watermark.
Is my data sent to a server?
No. Everything is calculated locally in your browser. Nothing you enter is uploaded, logged or stored.
Does it work on my phone?
Yes. It works in any modern browser on Android, iPhone, iPad, Windows, Mac and Linux — no app needed.