I'm wondering why there's a difference in the byte size and item count when an assortment of data stored on my internal drive is replicated on an external drive. Although sometimes the byte size and item count is identical, it's usually lower on the external drive. Here's an example, with three folders of mixed mp3, avi txt files. The first figures are for internal drive, the latter for the same items on the external drive. : Folder 1: 35,041,200,905 bytes (35.04GB on disk) for 121 items; 35,041,194,761 bytes (35.04GB on disk) for 121 items. Folder 2: 45,821,885,162 bytes (45.82GB on disk) for 732 items; 45,821,885,162 bytes (45.82GB on disk) for 726 items; Folder 3: 461,292,486,016 bytes (461.45GB on disk) for 82,889 items; 461,292, 486,016 bytes (461.45GB on disk) for 82,795 items.