You can quilt any size in a lap hoop! I have done a king, two full size and am currently working on a not quite queen (86" square). All done in a small lap hoop. I think my hoop is 14", certainly no bigger then 16". I love having my handquilting to sit with during TV time with hubby. Especially during the winter when it is so nice to have a nice warm snuggly quilt draped over my lap.
PS welcome to the board!