Circle Calculator
Free online circle calculator tool.
About Circle Calculator
The Circle Calculator is a dual-purpose tool that computes both the area and the circumference of a circle simultaneously based purely on its radius.
How Circle Calculator Works
- Step 1: Radius: Enter the radius of the circle (the distance from the exact center to the edge).
- Step 2: Calculate: The tool uses the built-in Math.PI engine to output both the total surface area and the outer perimeter (circumference).
Frequently Asked Questions
What if I only know the diameter?
The diameter is exactly twice the radius. Simply divide your diameter by 2, and enter that number into the radius field.
How accurate is the Pi (π) used here?
This calculator uses the standard IEEE 754 floating-point Pi provided by JavaScript engines, which is accurate to 15 decimal places.
What is circumference?
Circumference is the specific mathematical term for the perimeter of a circle—it represents the total length of the circular boundary.