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`r = "C" / (2* pi)`

Enter a value for all fields

The **Radius of a Circle from the Circumference** calculator * Circle * computes the radius (**r**) of a circle based on the circumference (C).

**INSTRUCTIONS:** Choose units and enter the following:

- (C) The circumference (perimeter) of the circle.

**Radius:** The calculator returns the radius in meters. However, this can be automatically converted to other length units via the pull-down menu.

The formula for the radius of a circle based on the circumference is:

r = C / 2π

where:

- r is the radius of the circle
- C is the circumference of the circle

**Related Circle Calculators:**

**Circle Area**- This computes the area of a circle given the radius**(A = π r**.^{2})**Segment Area f(r,θ)**- This computes the area of an arc segment of a circle given the radius (**r**) and angle (**θ**)**Segment Area f(r,h)**- This computes the area of an arc segment of a circle given radius (**r**) and the depth (**h**) into the circle.**Sector Area f(r,Θ)**- This computes the area of a sector (pie slice) of a circle given the radius (**r**) and angle (**Θ**).**Area of Annulus**- This computes the area of an annulus (ring) given the inner radius (**r**) and outer radius (**R**).**Radius -Center to a Point**- This computes the radius of a circle given the center point (**h,k**) and any other point (**x,y**) on the circle.**Circumference**- This computes the circumference of a circle given the radius (**C = 2 π r**).**Arc Lengths**- This computes the length of a cord segment (arc length) on a circle given the radius (r) and angle (**Θ**)**Circle within a Triangle**- This computes the radius of a circle inscribed within a triangle given the length of the three sides (**a,b,c**) of the triangle.**Circle around a Triangle**- This computes the radius of a circle that circumscribes a triangle given the length of the three sides (**a,b,c**) of the triangle.**Radius from Circumference**- This computes the radius of a circle given the circumference.**Circumference from Area**- This computes the circumference of a circle given the area.**Radius from Area**- This computes the radius of a circle given the area.**Radius from Cord**- This computes the radius of a circle based on the length of a cord and the cord's center height.