I may be wrong, but I assumed the weight of the paper was in reference to how think/thin the paper was. We have been using Staples 20lb multipurpose and copy paper for years, but decided to try this 20lb paper for the lower cost. This Hammermill paper is MUCH thinner than the Staples brand of the same weight. When we print on this paper, the paper gets creases on it from the printer rollers and it the smallest bend to the paper (i.e. picking up a piece from a desk) puts a permanent dent in it. We have never had this happen with any other brand of 20lb paper... not at all what was expected and a waste of money.