If you want the draperies to clear the window when fully open, refer to the stack back chart.
Width of Glass - This is the measurement of the window opening.
Stackback - This is the total stackback when the draperies are in their open position. The amount of space the drapes will fill.
Rod Width Needed - This is the measurement of the Rod that will be needed in order to have the draperies clear the window when open.