Hi, By example,
$ df --human-readable /dev/sdb2 Filesystem Size Used Avail Use% Mounted on /dev/sdb2 82G 66G 12G 86% /home $ df --si /dev/sdb2 Filesystem Size Used Avail Use% Mounted on /dev/sdb2 88G 71G 13G 86% /home In both cases, the output unit presented is G(iB) whereas a power-of-1000 unit (GB) was requested in the latter invocation.
