Math & Statistics Tools
Circle Calculator
Calculate radius, diameter, circumference, and area of a circle from any known value.
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What is Circle?
All circle properties derive from pi: d = 2r, C = 2 x pi x r, A = pi x r^2. This calculator solves for all values from any single input.
How it works
We solve for radius from the known value, then derive all other properties. Results are displayed with formulas for educational reference.
- Enter your input. Type or paste your input into the field above — the tool responds instantly.
- Review the result. Output updates live as you type. Everything runs entirely in your browser.
- Copy or download. Use the Copy button to grab the result, or Download to save it as a file.
Examples
Realistic sample
Type or paste any realistic input — the tool computes the result locally and instantly.
Common mistakes
Expecting a server round-trip
Nothing is uploaded — every tool in this category runs entirely in your browser.