How heavy is a ream of paper?

I was just wandering this! It says 20 lbs, so we tested it in our science lab. 10 Sheets weighs 46 grams. Doing dimensional analysis, you end up with 5.07 lbs/ream!

Well before a ream of paper is cut down to its 8.5x11 in sheets it is formed in huge sheets. This 20lb weight comes from what 500 of the large sheets would weigh before cutting them down. this gives you the weight, or thickness of the sheets. ie. 20lb, 24lb or 28lb.