From the big Bible update earlier this week:
• Not sure what size the Notification Bar said, but it was something fairly small, 2-300 MB, perhaps.
• When I first hovered over the icon, it said 0% of 2XX MB (I would have thought 27X MB, but that may well be wrong). -- The problem is that at that time I already had 4-5-6 resources in the Downloaded folder, and a couple more on the way. (And as you can see below, some of the biggest resources downloaded first.)
• After that I followed it all the way up to 98%, and the size was always claimed to be 238 MB.
• When it finished, I had 1,16 GB in new resources, plus SR 1...

That size calculator is seriously off!
(Another size issue can be found at BUGS when doing an Update Now between downloading and indexing.)