The weight of a certain type of paper is presented differently depending on the location where the paper is being produced and sold. In the United States, each specific type of paper is measured in pounds per 500 standard-sized sheets, and different types of paper have different standard sheet sizes.

*The basis weight of a paper is the designated fixed weight of 500 sheets, measured in pounds, in that paper's basic sheet size. It is important to note that the "basic sheet size" is not the same. for all types of paper.*For paper that is 24 lb. or higher, the correct envelope is one of equal weight to the paper. The correct envelope for paper up to 20 lb. should be one step heavier than the paper. For example, the proper envelope to use with a 20 pound paper would be one made from 24 pound paper. Determine the weight of your paper. This "weight," generally listed on the package, is not the weight of a single piece of paper. Rather, it is the weight of a ream—500 sheets— of paper, which is then cut into individual pieces of paper. On average, ink jet paper is 20 lbs. and fits four pieces of paper to a sheet.