In my repo (https://bitbucket.org/SRH/tower) the reported size is 1.7GB.
It actually was that large as someone comitted a lot of stuff he shouldn't have. I've removed that commits from the history a few days ago, but the repo still reports 1.7GB. When I run "git count-objects -v -H" it reports size-pack: 151.58 MiB
So I'm guessing there is something wrong on the size reported by bitbucket.