Grammage are the same weight paper having different cut size. However, a sheet of common copy paper that has a basis weight of does not have the same mass as the same size sheet of coarse paper (newsprint). In the former case, the standard ream is 500 sheets of paper, and in the latter, 500 sheets of paper. Here are some basic ream sizes for various types of paper. Units are inches except where noted. Sheets can be cut into four sheets, a standard for business stationery known conventionally as "letter sized paper". So, the ream became commonly used. The book-paper
Paper size the sheet of paper is folded in half widthwise, let "c" be the length of the new short side: "c" = . If we take the ratio of the newly folded paper we have: formula_3 Therefore, the aspect ratio is preserved for the new dimensions of the folded paper. Weights are easy to calculate as well: a standard A4 sheet made from 80 g/m paper weighs 5 g (as it is of an A0 page, measuring 1 m), allowing one to easily compute the weight—and associated postage rate—by counting the number of sheets used. The advantages of basing a paper