Circle Calculator

Calculate circle properties: area, circumference, diameter, and radius. Enter any value to find all others instantly.

Input Value

010

Circle Diagram

rd = 2rC
Radius (r)
Diameter (d)
Circumference (C)

Results

Radius (r)
0
r
Diameter (d)
0
d = 2r
Circumference (C)
0
C = 2πr
Area (A)
0
A = πr²

Circle Formulas

C = 2πr
Circumference from radius
A = πr²
Area from radius
d = 2r
Diameter from radius
π ≈ 3.14159
Pi constant

About Circle Calculations

A circle is a shape consisting of all points in a plane that are at a given distance (radius) from a given point (center). The circle calculator helps you find all properties of a circle when you know just one measurement.

Key Properties

  • Radius (r): Distance from center to edge
  • Diameter (d): Distance across through center
  • Circumference (C): Distance around the circle
  • Area (A): Space enclosed by the circle

How to Use

  1. Select which value you know
  2. Enter the value
  3. All other values calculate instantly
  4. Adjust precision as needed