Gratuito online circle calculator. Enter any one value (radius, diameter, circumference, or area) and instantly calculate all other circle measurements with formulas and step-by-step solutions.
This circle calculator helps you find all measurements of a circle when you know any one value. Whether you have the radius, diameter, circumference, or area, enter it and the calculator instantly computes the other three values using the fundamental formulas of circle geometry. Perfect for students, engineers, architects, and DIY enthusiasts.
The area of a circle is calculated using A = πr², where r is the radius of the circle. If you know the diameter, you can use A = π(d/2)².
First, find the radius using r = √(A/π), then calculate the circumference with C = 2πr. This calculator does both steps automatically.
Pi (π) is a mathematical constant approximately equal a 3.14159. It represents the ratio of a circle's circumference to its diameter and appears in all circle formulas.
This calculator is for 2D circles only. For spheres, you would need additional formulas involving volume (V = 4/3 πr³) and surface area.
Yes, this calculator uses JavaScript's built-in Math.PI constant (3.141592653589793) for maximum precision. Results are accurate to at least 10 decimal places.