NUMFMT(1)

NAME
numfmt - Convert numbers from/to human-readable strings

SYNOPSIS
numfmt [OPTION]... [NUMBER]...

DESCRIPTION

Reformat NUMBER(s), or the numbers from standard input if none are specified.

Mandatory arguments to long options are mandatory for short options too.

--debug
    print warnings about invalid input

-d, --delimiter=X
    use X instead of whitespace for field delimiter

--field=FIELDS
    replace the numbers in these input fields (default=1); see FIELDS below for details

--format=FORMAT
    use printf style floating-point FORMAT; see FORMAT below for details

--from=UNIT
    auto-scale input numbers to UNITs; default is 'none'; see UNIT below for details

--from-unit=N
    specify the input unit size (instead of the default 1)

--grouping
    use locale-defined grouping of digits, e.g. 1,000,000. This has no effect in the C/POSIX locale

--header[=N]
    print (without converting) the first N header lines; N defaults to 1 if not specified

--invalid=MODE
    failure mode for invalid numbers; MODE can be: abort (default), fail, warn, ignore

--padding=N
    pad the output to N characters; positive N will right-align, negative N will left-align; padding is ignored if the output is wider than N; the default is to automatically pad if a whitespace is found

--round=METHOD
    use METHOD for rounding when scaling; METHOD can be: up, down, from-zero (default), towards-zero, nearest

--suffix=SUFFIX
    add SUFFIX to output numbers, and accept an optional SUFFIX in input numbers

--unit-separator=SEP
    insert SEP between number and unit on output, and accept an optional SEP in input numbers

--to=UNIT
    auto-scale output numbers to UNITs; see UNIT below

--to-unit=N
    the output unit size (instead of the default 1)

-z, --zero-terminated
    line delimiter is NUL, not newline

--help
    display this help and exit

--version
    output version information and exit

  UNIT options:

none
    no auto-scaling is done; suffixes will trigger an error

auto
    accept optional single/two letter suffix: 1K = 1000, 1k = 1000, 1Ki = 1024, 1M = 1000000, 1Mi = 1048576,

si  accept optional single letter suffix: 1k = 1000, 1K = 1000, 1M = 1000000, ...

iec accept optional single letter suffix: 1K = 1024, 1k = 1024, 1M = 1048576, ...

iec-i
    accept optional two-letter suffix: 1Ki = 1024, 1ki = 1024, 1Mi = 1048576, ...

  FIELDS supports cut(1) style field ranges:

N   N'th field, counted from 1

N-  from N'th field, to end of line

N-M from N'th to M'th field (inclusive)

-M  from first to M'th field (inclusive)

-   all fields

Multiple fields/ranges can be separated with commas

FORMAT must be suitable for printing one floating-point argument '%f'. Optional quote (%'f) will enable --grouping (if supported by current locale). Optional width value (%10f) will pad output. Optional zero (%010f) width will zero pad the number. Optional negative values (%-10f) will left align. Optional precision (%.1f) will override the input determined precision.

Exit status is 0 if all input numbers were successfully converted. By default, numfmt will stop at the first conversion error with exit status 2. With --invalid='fail' a warning is printed for each conversion error and the exit status is 2. With --invalid='warn' each conversion error is diagnosed, but the exit status is 0. With --invalid='ignore' conversion errors are not diagnosed and the exit status is 0.

EXAMPLES

    $ numfmt --to=si 1000

    -> "1.0k"

    $ numfmt --to=iec 2048

    -> "2.0K"

    $ numfmt --to=iec-i 4096

    -> "4.0Ki"

    $ echo 1K | numfmt --from=si

    -> "1000"

    $ echo 1K | numfmt --from=iec

    -> "1024"

    $ df -B1 | numfmt --header --field 2-4 --to=si
    $ ls -l | numfmt --header --field 5 --to=iec
    $ ls -lh | numfmt --header --field 5 --from=iec --padding=10
    $ ls -lh | numfmt --header --field 5 --from=iec --format %10f

AUTHOR
Written by Assaf Gordon.

REPORTING BUGS
Report bugs to: bug-coreutils@gnu.org
GNU coreutils home page: <https://www.gnu.org/software/coreutils/>
General help using GNU software: <https://www.gnu.org/gethelp/>
Report any translation bugs to <https://translationproject.org/team/>

COPYRIGHT
Copyright © 2026 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>.
This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.

SEE ALSO
Full documentation <https://www.gnu.org/software/coreutils/numfmt>
or available locally via: info '(coreutils) numfmt invocation'