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.

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.

This calculator will calculate the area of a circle given its diameter, using the famous formula area = pi times (d/2) squared. It supports different units such as meters, feet, and inches. Just type into the …

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.

Need to know the area of a circle using just its diameter? Use our Diameter to Area Calculator to get fast, accurate results for all your circular measurement needs.

Calculate the area of any circle easily with our free online tool. Input radius, diameter, or circumference to get instant, accurate results with step-by-step explanations and visual representation..

Calculate using either radius or diameter measurements in various units including centimeters, inches, meters, and more. Choose your preferred decimal precision and π (pi) approximation level for …

Answer: The area of a circle using diameter can be found by the formula, Area = 1/4πd 2, where 'd' is the diameter of the circle and 'π' (pi) is a constant with a value of 22/7 or 3.14