The choice of box type will ultimately determine the dimensions of your speaker box. As observed, here are the typical box dimensions for each type: Table: Typical Speaker Box Dimensions You can enter the width, height, and depth in millimeters (mm), centimeters (cm), inches (in) or feet (ft). Just check the radio button to the right of the width text box to change the units. 10mm = 1cm 2.54cm = 1in or 1" 12in = 1ft or 1' Below that you can enter the box volume that will be displaced by the speaker driver itself. IkL7C.