My Terabyte hard drive only has 931mb free? [duplicate]

Question

I just used boot and nuke to wipe my hard drive and reinstall my OS systems. When selecting the hard drive I noticed that there were only 931gb free in my hard drive.

Is this normal? It sees like a strange number as I though terabyte drives held 1024gb.

Is some of the hard drive hidden? Are there any programs that can check?

Thanks in advanced for any help with this!

df -h returns the following:

Filesystem           Size  Used Avail Use% Mounted on
udev                 3.9G     0  3.9G   0% /dev
tmpfs                786M   18M  768M   3% /run
/dev/sda5            437G  5.7G  409G   2% /
tmpfs                3.9G   31M  3.9G   1% /dev/shm
tmpfs                5.0M  4.0K  5.0M   1% /run/lock
tmpfs                3.9G     0  3.9G   0% /sys/fs/cgroup
tmpfs                786M   20K  786M   1% /run/user/124
/home/*/.Private     437G  5.7G  409G   2% /home/*
tmpfs                786M  2.0M  784M   1% /run/user/1000

lsblk returns the following:

NAME           MAJ:MIN RM   SIZE RO TYPE  MOUNTPOINT
sda              8:0    0 931.5G  0 disk  
├─sda1           8:1    0   500M  0 part  
├─sda2           8:2    0 478.8G  0 part  
├─sda3           8:3    0   496M  0 part  
├─sda4           8:4    0     1K  0 part  
├─sda5           8:5    0 443.9G  0 part  /
└─sda6           8:6    0   7.9G  0 part  
└─cryptswap1   253:0    0   7.9G  0 crypt [SWAP]
sr0             11:0    1  1024M  0 rom   

EDIT: I am literally installing the dual boot system as we speak. Windows first, here is a breakdown of what Windows 10 sees:

So total size is 931.51GB. That is a very strange number.

Answer 1

The discrepancy with the displayed number is do to the fact that hard drive manufactures are aiming for a number closer to

1,000,000,000,000 bytes which is 1 TB.

while windows and Linux present you with a unit of 1024 not 1000 although on Windows this is GB and on Linux this is the more accurate GiB.

1 TiB would have to be 1,099,511,627,776 bytes.

If we go the nearest GiB with only 1,000,000,000 bytes this is the math:

1,000,000,000,000 bytes / 1024 = 976,562,500 KiB
976,562,500 KiB / 1024 ~= 953,674 MiB
953,674 MiB / 1024 ~= 931 GiB

However don't make the assumption that hard drive manufactures make disk platters that exactly add up to 1,000,000,000,000 bytes they do not. Still the same unit conversion discrepancies apply.

Answer 2

it's because Gigabyte (GB) can have different meanings in different contexts. When referring to computer memory, gigabyte is always a “power of two” = 1,073,741,824 bytes, but when measuring hard drive capacity it is often defined as 1,000,000,000 bytes. Generally, operating systems calculate disk and file sizes using binary numbers, so a new 500 GB drive you've just purchased would be reported by the OS as "465.66 GB" (meaning 465.66 GiB, GiB = Gigibyte). so 1 TB hard disk means 1,000,000,000,000 bytes and if you divide it by 1024^3 to convert it to Gigabytes, you see the result is: 931.322574615 GB