That would all depend on the model in question[1]. 2-3" blade is pocket knife size. If going by wiki[2], it defines pocket knife as 2-6". 6" is pretty big for a what one would define as a pocket knife though.

[1] http://images.google.com/images?q=leatherman&sourceid=op...

[2] http://en.wikipedia.org/wiki/Pocket_knife