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Circle Calculator

Choose a Calculation: Calculate Area and Circumference | Given Radius Calculate Radius and Circumference | Given Area Calculate Area and Radius | Given Circumference r =  Units:     meters feet inches     A =  C =

Circle Geometric Shape r = radius A = area C = circumference Π = Pi

Circle Formulas in terms of radius r: (Π = Pi)

Area of a circle:

A = Π * r²

Circumference of a circle:

C = 2 * Π * r

Circle Calculations:

Use the following additional formulas along with the formulas above.

• Given the radius of a circle calculate the area and circumference
  Given r find A, C
  • use the formulas above
• Given the area of a circle calculate the radius and circumference
  Given A find r, C
  • r = √(A / Π)
  • C = 2 * Π * r
• Given the circumference of a circle calculate the radius and area
  Given C find r, A
  • r = C / 2Π
  • A = Π * r²