--The controversy started when a guy in Australia posted a photo of his footlong with a measuring tape on top, showing that it's very clearly and very exactly 11 inches.

--And TONS of other people followed his lead, and posted their photos of undersized Subway footlongs.  Not just in Australia, either . . . these photos are coming from EVERYWHERE, including the U.S.

--There's one theory floating around that the bread starts at 12 inches but shrinks when it's toasted.  The other theory?  That Subway has NEVER served 12-inch bread, and it took someone THIS LONG to notice.

--So far there's no official response from Subway.

(--Here's the original 11-inch photo (above).   CLICK HERE to access Subway's Facebook page featuring dozens of photos of 11-inch subs posted by people around the world.)