Circle Formula Calculator: Find Area, Circumference, Diameter & Radius

Calculate Circle Properties

Select an input type and enter its value.

Unlock the mysteries of circles with our intuitive Circle Formula Calculator. Quickly determine the area, circumference, diameter, or radius by simply entering one known value. This versatile tool is perfect for students, engineers, and anyone needing quick, accurate geometric calculations for homework or projects.

Formula:

Key Circle Formulas:

  • Area (A): A = πr² (where r is radius, π ≈ 3.14159)
  • Circumference (C): C = 2πr = πd (where d is diameter)
  • Diameter (d): d = 2r
  • Radius (r): r = d/2

Input one known value (radius, diameter, area, or circumference) and let our calculator find the rest!

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