Here is a simple online calculator to calculate the angular size (α) using the known values of linear size (D) and the distance to the object (L). The angular size is the angle formed when the object is seen from a point of distance. It is the angle from the point of view to the visual diameter of the object at distance and is denoted by α. The linear size is represented by D, and is the approximate visual diameter of the object from the point of view. The distance of the object from the point of view is denoted by L. In the calculator below, enter the values for Linear Size (D) and distance to the object (L) to obtain the Angular Size (α).