A mil is one one-thousandth of an inch (0.001″ or 1/1000″). When referring to laminating film, this measurement indicates the total thickness of a single layer of the film (which includes both the adhesive and the film itself). Because most lamination applications are double-sided, the actual thickness of the film used will usually be doubled. For example, a document laminated with a 3 mil laminating pouch (or comparable roll laminating film) will have 3 mils of laminating film on each side of the paper, which is a total of 6 mils. ; 5 mil would be a total of 10 mils; 10 mils would be a total
of 20 mils.
Laminating pouches are most commonly sold in thicknesses of 3, 5, 7, and 10 mils. The 3 mil pouches are the thinnest, and can be folded easily. 5 mil pouches are slightly thicker, but are still easy to score or fold. Pouches that are 7 mils thick are quite rigid but are still slightly pliable. 10 mil laminating pouches are the most rigid