Answer by Bence Kiglics for A standard tool to convert a byte-count into human KiB MiB etc; like du, ls1

I had the same problem and I quickly came up with a simple solution using awk's log() function:

awk '
  BEGIN {
    split("B,kiB,MiB,GiB", suff, ",")
  }

  {
    size=$1;
    rank=int(log(size)/log(1024));
    printf "%.4g%s\n", size/(1024**rank), suff[rank+1]
  }
'

And the precision lost in using float numbers is not that bad since that precision will be lost anyways.