Circle Calculator

With our Circle Calculator, you can determine the area, circumference, radius, and diameter of a circle by entering just one known value. The calculator will automatically calculate the other values.

Formulas

This calculator uses the following formulas:

Radius = Diameter / 2

Circumference of a circle = 2 × π × Radius

Area of a circle = π × Radius 2

Surface area of a sphere = 4 × π × Radius 2

Where π is the constant (3.141592654)

Circle & Sphere Calculator

Circle and Sphere Calculator

sq. units

sq. units

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