Math K-Plus

User Friendly Area Of A Circle Calculator

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How To Find The Area Of A Circle

Let's look at the geometric characteristics of a circle. But first, please review the definition of Area Of Two-Dimensional Shapes.
  • The widest length is through the center of the circle. This length is known as the Diameter of the circle; In the example, it is shown as "D" in the diameter.
  • If you draw a line from the exact center of the diagram to any edge of the circle, this is called the Radius; In the example, the radius is shown as "R". Also the radius is half the value of the diameter.
  • To compute the Area Of A Circle, you will use Pi as part of the formula.
  • Special note, the diameter of a Circle must be greater than zero.

Area Of A Circle Formula
Formula = π × radius × radius =
Formula = π × r2


Area Of A Circle Calculator
Field Name User Input
Length Of R
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Your Answer
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Correct Answer

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