Math

Circumference to Radius Calculator

Find a circle's radius and diameter from its circumference.

Parameters Live Compute
Calculated Output
Radius 5
Diameter 10
Area 78.54
Formula: radius = circumference ÷ (2π)
Step-by-Step Breakdown
1. Values used:
2. Circumference = 31.416
3.
4. Radius = 5
5. Diameter = 10
6. Area = 78.54
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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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