Area of a Circle Calculator

Calculate the area of a circle using the radius, diameter, or circumference with the circle area calculator.


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How to Calculate the Area of a Circle

A circle is a round shape with no corners or edges where each point along its edge is equidistant from the center. The area of a circle is the amount of space the shape occupies.

Think of the area of a circle as the region of a two-dimensional plane it occupies or encloses.

There are a few ways to find the area of a circle.

The first way to calculate area is to use the circle area calculator above. The second way is to use a circle area formula.

Circle Area Formulas

To calculate the area of a circle, you’ll need its radius, diameter, or circumference.

Then, use one of the following formulas.

Find Area Using Radius

The radius is the length of a straight line from the center of a circle to the outer edge. The most commonly used formula to find the area given the radius of a circle is:

A = π × r²

Thus, the area of a circle A is equal to pi times the radius r squared.

Graphic showing the formula to find the area of a circle where the area is equal to pi times the radius squared

Find Area Using Diameter

The diameter is the length of a straight line from one edge of the circle to the opposite edge. It is twice the length of the radius.

The formula to find the area given the diameter of a circle is:

A = π × (d / 2

The area A is equal to pi times the diameter d divided by 2, squared.

Find Area Using Circumference

The circumference is the length of the outer edge around the perimeter of the circle. The formula to find the area given the circumference of a circle is:

A = π × (C /

The area A is equal to pi times the circumference C divided by 2 times pi, squared.

Give our circle calculator a try and solve a circle’s dimensions, including the radius, diameter, and circumference.