Because the standards of hard disk manufacturers and computer computing capacity are inconsistent, 256G hard disk=256000000000 bytes based on the actual capacity of the manufacturer.The computer is calculated as a multiple of 2, 2 ^ 10=1024 bytes=1KB, 1024KB=1MB, 1024MB=1GB. So the capacity of 256GB hard disk on the computer is shown as: 256GB * (1000 * 1000 * 1000)/(1024 * 1024 * 1024), about 238.3GB.
It is normal that the actual capacity of the hard disk is less than the nominal capacity, because there are some spare sectors in it. If the hard disk has bad tracks, the backup sector can be called to repair them.
