Circle Calculator

Calculate all properties of a circle with just one known value

Calculate from:

Value:

units

Enter a positive number

Decimal Precision:

Diameter (D) Radius (r)

Circle Formulas

Diameter (D) D = 2r
Circumference (C) C = πD = 2πr
Area (A) A = πr²

Fast Calculations

Get instant results for any circle property with our optimized calculator.

Multiple Inputs

Calculate from radius, diameter, circumference, or area - whichever you know.

Visual Representation

Understand circle properties with our clear visual diagram.

About Circle Calculator

Our Circle Calculator is a powerful online tool designed to help students, teachers, engineers, and anyone working with circular shapes to quickly calculate all properties of a circle from any single known value.

How to Use the Circle Calculator

Select the property you know (radius, diameter, circumference, or area)
Enter the known value in the input field
Choose your desired decimal precision
Click "Calculate" to see all circle properties

Applications of Circle Calculations

Circle calculations are fundamental in many fields:

Mathematics Education: Essential for geometry students learning about circular shapes
Engineering: Used in designing circular components, pipes, wheels, and gears
Construction: Important for circular structures, arches, and landscaping
Manufacturing: Needed for producing circular objects and quality control
Science: Used in physics calculations involving circular motion

Understanding Circle Properties

A circle is a perfectly round shape where all points on its edge are equidistant from the center. The key properties of a circle are:

Radius (r): The distance from the center to any point on the circle
Diameter (D): The distance across the circle through the center (2 × radius)
Circumference (C): The distance around the circle (π × diameter)
Area (A): The space contained within the circle (π × radius²)

The constant π (pi) is approximately 3.14159 and represents the ratio of a circle's circumference to its diameter.