Circumference & Area Calculator
Compute the circumference and area of a circle from either radius or diameter. This free tool supports your local number format and shows instant results as you type. View the formulas (2πr and πr²), choose units, and copy results in one click.
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What is the circumference of a circle?
The circumference of a circle is the distance around the outer edge or boundary of the circle. It is the total length of the circle's perimeter. The circumference is calculated using the formula:
Circumference = 2 x π x r
where r is the radius of the circle and π (pi) is a mathematical constant that is approximately equal to 3.14.
The circumference is an important property of a circle, and it is used in various mathematical and scientific calculations involving circles, such as finding the length of an arc, the area of a sector, or the volume of a cylinder.
What is the area of a circle?
The area of a circle is the total amount of space inside the boundary or circumference of the circle. It is calculated using the formula:
Area = π x r^2
where r is the radius of the circle and π (pi) is a mathematical constant that is approximately equal to 3.14.