The website Paper Sizes provides a wealth of information about paper sizes ancient and modern. As they say, before we were blessed with international standards in this area, we used a charmingly antique vocabulary to talk about paper sizes. Before paper making was industrialized, the sizes were determined by the size of the mould and the deckle, and this in turn was limited by the length of the human arm.

First, Uncut Drawing Paper Sizes:

Then Uncut Printing Paper Sizes:

For more in this vein, please see Demy octavo, and Paper sizes.