Math
Circumference to Radius Calculator
Find a circle's radius and diameter from its circumference.
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Work backwards from a circle's circumference to its radius, diameter and area.
The math behind it
Since circumference = 2πr, the radius is circumference ÷ (2π).
Worked Example
Circumference 31.42 → radius 5, diameter 10.
Frequently Asked Questions
How do I get the diameter directly?
diameter = circumference ÷ π.
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