All I know is that I've found that it's cheaper and bigger if you buy it at the hardware store than the food store. It's in the paint section because it's used to strain paint (they also use it for polishing tile). For like $4 you can get something that's maybe 15 feet long and 3 feet wide. And no shipping cost if you buy local.
http://www.homedepot.com/p/QEP-36-in-Cheese-Cloth-76030Q/100169798#.UjOtKn-E7Kc
http://www.homedepot.com/p/QEP-36-in-Cheese-Cloth-76030Q/100169798#.UjOtKn-E7Kc