Then I just did some analysis and found that these are the default sizes of the corresponding files, but actually on disk it will store this much size.
I found one more interesting point, for me atleast, the actual size is increasing on some increment basis, which is displayed in table as "Increment in bytes". Till that size on disk, the actual size is incrementing but size on disk is not changing.
What I understand from this is, In hard disk, file will get space according increment.
|File Format||Size stored on Disk||Actual Size||Increment in bytes|
(MSOffice 97-2003 format)
|28KB, 28672B||26KB, 26112B||512B|
(MSOffice 2007 format)
|12KB, 12888B||9.65KB, 9886B||1B|
If I'm wrong in any sentence, please let me know. I will try to update my knowledge.