The blue max site shows that when folded down, it's 17" long, 8" tall and 4" wide.

Over on ADVrider, a lot of people like this chair for a mobile, take on the bike chair:

http://www.alitedesigns.com/monarch-camp-chair-5

It's more costlier, but it's a little smaller for those looking for small as possible, gets great reviews, and they do run sales throughout the year that gets it nearly half price. Packed size is 4.5" x 13".

However, the bluemax one sits up higher, and that in itself may be the winning factor. Depending on comfort factor, and a even better price, I may be interested in 2...