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.

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.

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.

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.

Use our free Circle Calculator to instantly find area, circumference, radius, and diameter of any circle. Simple, accurate calculations with step-by-step examples and formulas.

Free online circle area calculator. Calculate the area of a circle using radius, diameter, or circumference with step-by-step solutions and visualizations.

Calculate the area of any circle with this free online Circle Area Calculator. Includes step-by-step calculations, unit conversion, and circle visualization.

Calculate the area of a circle based on its radius or diameter. Fast, accurate, and completely free. Includes the calculation formula and practical examples.

Free online area of a circle calculator which helps you calculate the are of any circle, given its radius. Supports many different metrics such as in, ft, yd, mm, cm, meters, etc.