It is the same as calculating the perimeter of any polygon such as triangle, square, and rectangle. · the circumference of a circle is equal to the length of its boundary, but the circle is a curved shape, its circumference cant be measured with a ruler. Online circumference of a circle calculator - given a radius in mm, cm, meters, km, inches, feet, yards, miles, and others, calculate the circumference of any circle. If you unroll the outer edge of a circle, it will form a straight segment whose length is three diameters plus a little bit more. Use this free circumference calculator to find the area, circumference and diameter of a circle. · the circumference of a circle is the distance around the boundary of the circle. The formula for circumference is based on the constant π (pi), which is an irrational number approximately equal to 3. 14159. Circumference is from latin meaning carrying around. Circumference of a circle … The correct way to find the … Π is the ratio of the circumference to the diameter of any circle. The circumference of a circle is the distance around it, but if, as in many elementary treatments, distance is defined in terms of straight lines, this cannot be used as a definition.