Ok, I think I just answered my own question. I went to the AHS web page and this is the guidelines they use to classify hostas according to size.
Table of Relative Hosta Size
Hosta Size Leaves Mature Plant
Dwarf <2.0 sq. in. <4" tall
Miniature 2.0 to 6.0 sq. in. 4" to 6" tall
Small 6.0 to 25 sq. in. 6" to 10" tall
Medium 25 to 81 sq. in. 10" to 18" tall
Large 81 to 144 sq. in. 18" to 28" tall
Giant >144 sq. in. >28" tall