text: There are to many variables to answer absolutly, what weight of paper are you using? (20 pound, 25 pound, 18 pound), are you using A4 or standard US paper? glossy or matte finish?\n\nAll of these things are needed for an answer, but if I assume that you are using standard US 20 pound matte paper (like you buy for your office copy machine) then it weights roughly 6 pounds.  I will put the formula here later.  I have it at home (how strange is that?)\n\n** Edit **\n\nO.K.  I had the formula but now I don't.  Basically it is something like this:\n\nyou purchase 20 pound paper, well. . . that is the weight of 1,000 sheets of 11x17 (in the US) paper, also called the M Weight (M=1,000 cute, eh?).  Now, 1,000 sheets of 11x17 is 4 reams of 8.5x11 paper.\n\nSo 4 reams = 20 pounds then you divide it by 4 (20/4=5) so you have 5 pounds per ream.\n\nRemember that is for 20 pound white uncoated paper.  If you have colored paper or coated paper, it will change and you may not have 500 sheets in a ream. (some paper comes in 480 sheet reams)\n\nThis formula works for 24 pound, or 110 pound and anything in between.\n\nHope you have the info you need.  if you need more detail, let me know by leaving more in the question.