It depends on what you plan to put inside it. If you are using a custom-built storage cabinet, for example, the depth will depend on how many shelves or compartments there are and where they are positioned. Typically, a 16" (40.6cm) to 24 " (60.96cm) deep storage cabinet is sufficient for most people's needs; however, some may need deeper cabinets if they have bulky items like large tools that can't fit in smaller ones without being stacked up high.