Ziplock Bag Sizes: How To Measure ClearZip Bag Dimensions the right size ClearZip reclosable zip locking bags is easy. First determine the size of your content. Usable space inside a ClearZip bag is measured side to side for width. The length of the bag is measured from zipper track to the bottom of the bag. To fit larger, rigid items through the opening, add half an inch to the width of your content. If it is a slider lock, add one and a half inches.  For bulky items or a loose fit, add up to two inches to both dimensions (length and width).Now you know how to determine the zip lock bag dimensions find your ClearZip® recloasble bag at