I generally export to 100 ppi on these boards, though the maps I have been posting to my G+ page, and any of those maps reposted here, are all 300 ppi, but at scales of only 8.5 x (up to) 22 inches for pictorial tutorials, and up to 11 x 17 for map scale. When I post a 100 ppi file, it can be up to 24 x 36 inches, posted here direct - and almost always as JPG.