Another way of categorizing paper is by weighing - not just one sheet, but 500 sheets of that particular paper. For text/bond paper, the size of the sheets measures 17" x 22". For example, 500 sheets of 20 pound paper weighs 50 pounds and is referred to as having a basis weight of 50.
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. Southworth has a wide selection of # in 24 lb weight to match all our paper. We also produce to enhance the importance of your document.