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

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.

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.

Terminology Although often referred to as the area of a circle in informal contexts, strictly speaking, the term disk refers to the interior region of the circle, while circle is reserved for the …

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. It is measured in square units.

Jul 2, 2025 · This calculator determines the area of a circle using either the radius or the diameter. You may also enter a custom value for π, or use the default value of 3.14159.

Area of circle calculator using formulas A = πr², A = πd²/4, and A = C²/4π. Calculate area of a circle instantly from radius, diameter, or circumference with step-by-step solutions.

Area of a circle The area of a circle is the plane region bounded by the circle's circumference. The region shaded in gray inside of circle A above is its area. The area of a circle can be found …

Oct 29, 2025 · To find the area of a circle, use the formula A = π • r2, where r is the radius of the circle. If you only know the diameter of the circle, then use the formula A = π • (d/2)2 where d …

Oct 25, 2023 · What is the area of a Circle – learn how to find its surface area with formulas and solved examples