When 0 Equals 9.66%

The disk usage bar appears to be about 9.66% of the way full -- 23 of 238 pixels on my screen.

Do the math:

0 MB/25 MB = 9.66%

0 MB = 2.415 MB

Does this mean I get 2.415 MB less than the 25 megabyte allocation? Or does the "zero equals NOT zero" rule mean I get infinite space? ;-)