Circle Calculator
Compute a circle's radius, diameter, circumference and area from one known value.
Input Data
Which value you provide.
Input
Results
Derived radius.
5same unit
Derived diameter.
10
Derived circumference.
31.4159
Derived area.
78.5398
At a glance:d = 2r; C = 2πr; A = πr². Given one, derive the rest. Complements circle-area and circle-circumference.
Formula
d = 2r.
C = 2πr.
A = πr².
How to Use
- Pick the known value and enter it.
- The tool returns the other three.
Case Studies
r=5
d=10; C=31.42; A=78.54.
FAQ
Enter area to get radius?
Yes — r = √(A/π), then d, C follow.
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References
Content review: Calculatorism Science Team. Results are for reference only; please refer to the relevant authorities for the official figures.