Diameter is the distance across a circle through its center point. The diameter of a circle is the length of the line through the center and touching two points on its edge. The diameter of a circle is also a chord. A diameter is a chord that runs through the center point of the circle. It is the longest possible chord of any circle. The center of a circle is the midpoint of its diameter. That is, it divides it into two equal parts, each of which is a radius of the circle.
The mathematical formula for Diameter is:
Diameter = 2r
Where R=Radius of the circle