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

As of v. 8.21, coreutils includes numfmt:

numfmt reads numbers in various representations and reformats them as requested.
The most common usage is converting numbers to / from human representation.

e.g.

printf %s\\n 5607598768908 | numfmt --to=iec-i

5.2Ti

Various other examples (including filtering, input/output processing etc) are presented HERE.

In addition, as of coreutils v. 8.24, numfmt can process multiple fields with field range specifications similar to cut, and supports setting the output precision with the --format option
e.g.

numfmt --to=iec-i --field=2,4 --format='%.3f' <<<'tx: 180000 rx: 2000000'

tx: 175.782Ki rx: 1.908Mi