Calculate circle circumference, radius, and diameter instantly. Free online circumference calculator with unit conversion and visual diagram. Supports cm, m, in, ft.
This tool calculates the circumference, radius, and diameter of a circle. Enter any known value (radius, diameter, or circumference) and the calculator will instantly compute the other two measurements. Supports multiple units including metric and imperial.
The circumference of a circle is calculated using C = 2πr (where r is the radius) or C = πd (where d is the diameter). π is approximately 3.14159...
Yes! Enter the circumference value and select 'Circumference' as the known value. The calculator will compute: d = C / π
This calculator supports centimeters (cm), meters (m), millimeters (mm), inches (in), feet (ft), kilometers (km), yards (yd), and miles (mi).