Did you notice the difference in file size between the Size column and Details Pane? One shows 1KB and one just at 79 bytes. Not much a big deal but it’s interesting knowing how Windows Explorer decides the size of a file.
The value in the Size column is always calculated in KB (kilobytes), regardless of how small or large the file is. And it’s always rounded up to the nearest KB. For example, the Windows8desktop file shown above is only in 79 bytes but is rounded up to 1 KB in Size column. Unless a file that is truly in 0 byte, it’s better not showing in 0 byte, isn’t it?
The value in the detail pane, on the other hand, uses a much more adaptive units in three significant digits: byte, KB, MB, or GB, all depending on how big or small the file is. The result, for example, a file in 19465 bytes (equals 19.0088 KB) shows up in Size column as 20KB but in Details Pane as 19.0 KB.
In another words, Windows Explorer uses different round-up method in these two places.
[via Old New Thing]