The area of a circle calculator will compute the surface of a circle using a radius or a diameter.

Aug 1, 2025 · Use this circle calculator to find the area, circumference, radius or diameter of a circle. Given any one variable A, C, r or d of a circle you can calculate the other three unknowns.

See How to Calculate the Area below, but first the calculator: Enter the radius, diameter, circumference or area of a Circle to find the other three.

In geometry, the area enclosed by a circle of radius r is πr2. Here, the Greek letter π represents the constant ratio of the circumference of any circle to its diameter, approximately equal to 3.14159.

Use the circle area calculator to calculate the area, diameter, circumference or radius of a circle.

Area of a circle, formula for area explained with examples, pictures, interactive examples and quiz.

The area of a circle is the space enclosed within the boundary of a circle. It is calculated using the formula A = πr^2, where 'r' is the radius of the circle.