Post #1088135

There are (mainly) 3 reasons for that: - TB vs TiB: Computers don't count drive space in metric units, they count it in powers of 2. This means that, for you, 1 TB is 1000 GB, while for a computer, 1 TiB is 1024 GiB. Drive manufactirers take advantage of this, and only count space in metric (TB). So when you plug the drive into your computer, and it converts to GiB, you end up with 1 TB = 931.3 GiB. Windows hasn't helped this confusion, I remember it doing something weird like counting in GiB and displaying it as GB. - Reserved space: Many OSes reserve some space on their drives for special stuff. This is especially the case with Linux and ext4, where it by default reserves a percentage of the drive to root. This is to optimize distribution of files around the disk, which limits fragmentation. The system slowly frees more of this space as you fill up the disk, and at the end it should leave you with 100% of the space. - Formatting: Empty drive space isn't the same as usable drive space. In order to use a drive you need to format it, which doesn't just blank it. Formatting a drive adds a filesystem to it, which is what allows you to write files and folders to it. This filesystem takes up some space, and reserves more space for inodes and, in some cases, a filesystem journal. Some filesystems have even more features that also take up some space.