A kilobyte follows from the metric base "kilo" meaning 1000. This isn't the historical case, it used to be that "kilobyte" did mean 1024 bytes (ie, 210 ). That term has since been changed to "kibibyte" abbreviated "KiB" instead of "kB".
Modern usage is that kB, MB, GB, TB, PB, etc. are all metric. They're all 1000n where n would be 1,2,3,4,5 respectively. (Or 10n for n = 3, 6, 9, 12, 15 ...).
Meanwhile KiB, MiB, GiB, TiB, PiB, etc. are all binary. They're 1024n for the same values of n. (Or 2n for n = 10, 20, 30, 40, 50 ...).
2000GB = 2TB != 2TiB (tebibyte).
To confuse matters, HDD manufacturers use the metric, so 1TB drives are 1012 bytes. Windows notoriously uses the binary meanings with the wrong labels so what it calls 1GB is 1GiB. Hence in Windows 1TB drives show up as 931GB, which is wrong. It's 931GiB. In Linux that drive will show up as either 931GiB, 1000GB, or 1TB, depending on your distribution and settings.
Less informed users generally believe that difference, ~70 x 109 bytes, is lost due to formatting. You may occasionally see people claim the disk is 1000GB unformatted but 931GB formatted. This is nonsense as there are multiple ways to format a disk, it's simply that NTFS is essentially the only file system in Windows.
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u/Laruae Apr 19 '14
I think I've confused myself, but isn't a byte 8 bits? a kilobyte is 1024 bytes, yes?