As a result of computer simulation step through rotating variable set of parallel chords, for ellipses any shape and size, determined average diameters, their slopes, two variants of averages chords, equivalent diameters. Found that an infinite set of averages chords, each step through sets, form subellipse averages chords, and the relation the average chord to the co-rotational diameter in any stepping infinite set of parallel chords and the arithmetic average of these averages chords to the average diameter of the ellipse, is constant ( /4). Shows the value of inequality average and equivalent diameters. Results are presented as summary tables and graphics, convenient for practical application.