Circle Calculator
Find area, circumference, diameter, and radius of any circle.
Results
Area-
Circumference-
Diameter-
Radius-
Formulas-
What is a Circle Calculator?
A circle calculator computes the key properties of a circle—area, circumference, diameter, and radius—given any one known value. It is essential for geometry, engineering, and design tasks.
How to Use
- Choose whether you know the radius or diameter.
- Enter the known value in the input field.
- Click Calculate to see all circle properties.
Frequently Asked Questions
What if I only know the circumference?
You can work backwards: radius = C / (2π) and diameter = C / π. Enter the radius after dividing.
Can I use this for spheres?
No, this tool is for 2D circles only. Use our Volume Calculator for spheres.
Are the results exact?
Results use π �?3.14159 and are rounded to 4 decimal places for display.
Is this tool free?
Yes, BestCalc calculators are completely free and run entirely in your browser.