Circle Calculator

Calculate area, circumference, radius, and diameter of circles

Enter any one measurement to calculate all circle properties. Choose from radius, diameter, circumference, or area.

Formulas

Area = π × r²

Circumference = 2 × π × r

Diameter = 2 × r

Other Titles
Understanding Circle Calculator: A Comprehensive Guide
Explore circle properties, formulas, and real-world applications in geometry and engineering

Understanding Circle Calculator: A Comprehensive Guide

  • Circles are fundamental geometric shapes with unique properties
  • Understanding circle calculations is essential in many fields
  • Circle formulas form the basis for advanced mathematical concepts
A circle is a perfectly round geometric shape where all points on its boundary are equidistant from the center. This distance is called the radius.
Circles appear everywhere in nature and human design, from wheels and gears to planets and atoms. Understanding their properties is fundamental to geometry, physics, and engineering.

Basic Examples

  • A circle with radius 5 has diameter 10, circumference 31.42, and area 78.54
  • The wheel is one of humanity's most important circular inventions
  • Planets follow approximately circular orbits around stars
  • Many architectural elements use circular geometry