Circle Calculator (area, circumference)
From the radius, get a circle's diameter, circumference and area.
Result
Diameter
10.0000
Circumference
31.4159
Area
78.5398
How it works
Area = π·r² · Circumference = 2·π·r
Enter the radius. The tool returns the diameter (2r), the circumference (2πr) and the area (πr²). Example: radius 5 → area ≈ 78.54.
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Frequently asked questions
How do I find the area of a circle?
Multiply π by the radius squared: area = π·r².
What is the circumference formula?
Circumference = 2·π·r (or π × diameter).
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