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.

The formula to calculate the area of a circle using radius is as follows: Area of a circle = π × r2. And, to calculate the area of a circle using diameter use the following equation: Area of a circle = π × (d/2)2. …

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 is 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.

Oct 25, 2023 · The area of a circle can be calculated using three different formulas. The formulas are used based on whether the radius, diameter, or circumference is known to us. Each of the three …

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 using the …

Jul 23, 2025 · Circle formulae are basic formulas of circles in geometry. The formula for calculating a circle's circumference, or perimeter, is C = πd or C = 2πr, where "d" is the diameter and "r" is the …

Alternatively, the space occupied within the boundary/circumference of a circle is called the area of the circle. The formula for the area of a circle is A = πr 2, where r is the radius of the circle. The unit of …

Apr 29, 2025 · Learn how to calculate the area of a circle with step-by-step examples. Includes formulas, derivation, practical applications, and practice problems...

Remember: The formula for the area of a circle is based on the circle's radius not its diameter. If a circle's radius is doubled, then how much did its area increase? Since the formula for the area of a …