Simply, ID refers to the “inner diameter” of the label roll and OD refers to the “outer diameter” of the roll.
This is important when determining the method of application. If a label is being machine applied it is important to know the size of the roll that will fit onto the label applicator. This is measured by measuring from one outside edge to another of the finished roll. A roll too large will not fit into the input space provided and a roll too small will require far too many roll changes for adequate productivity. When encountering a significantly small space for your input roll, label applicators will often use a smaller core, or inner diameter size, in order to maximize the amount of footage fitting into that space. For example, if your machine’s Maximum OD is 4-1/2” often times the product will be supplied on a 1” core to ensure most of the space taken up is with labels.