Grammage greater strength. Paper weight is sometimes stated using the "#" symbol. For example, "20#" means "20 pounds per basis ream of 500 sheets". When the density of a ream of paper is given in pounds, it is often accompanied by its "M weight". The M weight is the weight (in pounds) of 1000 cut sheets. Paper suppliers will often charge by M weight, since it is always consistent within a specific paper size, and because it allows a simple weight calculation for shipping charges. For example, a 500-sheet ream of 20# copy paper may be specified "10 M". 1000 cut
Paper × 841 mm). A1 is half the size of a sheet of A0 (i.e., 594 mm × 841 mm), such that two sheets of A1 placed side by side are equal to one sheet of A0. A2 is half the size of a sheet of A1, and so forth. Common sizes used in the office and the home are A4 and A3 (A3 is the size of two A4 sheets). The density of paper ranges from for tissue paper to for some speciality paper. Printing paper is about . Paper may be classified into seven categories: Some paper types include: