Convert between actual Hard drive sizes and logical sizes
Hard drive manufacturers quote every 1,000 bytes as 1 Kb, whereas a computer will
call 1,024 bytes as 1 Kb. On big hard drives, this does add up, giving the impression that you
buy 1 Tb hard drive, and it appears as 921 GB.
There is FAT32 overhead also, but this is the main reason for the discrepancy.
To calculate the physical (manufacturer’s) size from the the logical (Computers) size,
multiply it by 1.073741824 – and add a bit to round it up.