Circle Calculator

Enter diameter or radius


Circle - one of the simplest shapes described by the so called Euclidean geometry. The circle is a collection of all points on any one plane in a specific distance from one point called the center. The word as we know it today comes from the ancient greek κίρκος (kirkos), which stands for “ring” or “hoop”.

Equation form:

r = d
d = 2 * r
circumference = 2 * π * r
area enclosed = π * r²

About Circle Calculator tool.

Remember this tool should be used only to calculate area, perimeter or volume of a figure. The results we provide are accurate, but rounded to the 12th decimal place. It accepts scientific notation and converts immediately.