As with most storage mediums, you don't get the full amount listed. There are a few reasons for this: 1) the actual format of the drive takes up space (NTFS, FAT32, etc) 2) the main reason is that manufacturers usually list storage capacity as base 10, rather than base 2 (binary). Computers work in binary, so a Gigabyte is actually 1024MB, but the manufactures list a GB as 1000MB. So that's why when you start approaching multiple TB storage, you are "losing" 200+ MB. Of course, it could just be a glitch. Edit: A really interesting read is the use of gibibyte vs gigabyte. It's a bit misleading that OS's use the SI prefixes for decimals when referring to binary units.