NUMFMT

Section: User Commands (1)
Updated: February 2026
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NAME

numfmt - Convert numbers from/to huma-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.

X'tty: link https://www.gnu.org/software/coreutils/manual/coreutils.html#numfm-debug'--debugX'tty: link'

print warnings about invalid input

X'tty: link https://www.gnu.org/software/coreutils/manual/coreutils.html#numfm-d'-d, --delimiter=,XX'tty: link'/

use X instead of whitespace for field delimiter

X'tty: link https://www.gnu.org/software/coreutils/manual/coreutils.html#numfm-field'--field=FIELDSX'tty: link'

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

X'tty: link https://www.gnu.org/software/coreutils/manual/coreutils.html#numfm-format'--format=FORMATX'tty: link'

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

X'tty: link https://www.gnu.org/software/coreutils/manual/coreutils.html#numfm-from'--from=UNITX'tty: link'

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

X'tty: link https://www.gnu.org/software/coreutils/manual/coreutils.html#numfm-fro-unit'--from-unit=NX'tty: link'

specify the input unit size (instead of the default 1)

X'tty: link https://www.gnu.org/software/coreutils/manual/coreutils.html#numfm-grouping'--groupingX'tty: link'

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

X'tty: link https://www.gnu.org/software/coreutils/manual/coreutils.html#numfm-header'--header[=N]X'tty: link'

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

X'tty: link https://www.gnu.org/software/coreutils/manual/coreutils.html#numfm-invalid'--invalid=MODEX'tty: link'

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

X'tty: link https://www.gnu.org/software/coreutils/manual/coreutils.html#numfm-padding'--padding=NX'tty: link'

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

X'tty: link https://www.gnu.org/software/coreutils/manual/coreutils.html#numfm-round'--round=METHODX'tty: link'

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

X'tty: link https://www.gnu.org/software/coreutils/manual/coreutils.html#numfm-suffix'--suffix=SUFFIXX'tty: link'

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

X'tty: link https://www.gnu.org/software/coreutils/manual/coreutils.html#numfm-uni-separator'--unit-separator=SEPX'tty: link'

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

X'tty: link https://www.gnu.org/software/coreutils/manual/coreutils.html#numfm-to'--to=UNITX'tty: link'

auto-scale output numbers to UNITs; see UNIT below

X'tty: link https://www.gnu.org/software/coreutils/manual/coreutils.html#numfm-t-unit'--to-unit=NX'tty: link'

the output unit size (instead of the default 1)

X'tty: link https://www.gnu.org/software/coreutils/manual/coreutils.html#numfm-z'-z, --zero-terminatedX'tty: link'

line delimiter is NUL, not newline

X'tty: link https://www.gnu.org/software/coreutils/numfmt#numfm-help'--helpX'tty: link'

display this help and exit

X'tty: link https://www.gnu.org/software/coreutils/numfmt#numfm-version'--versionX'tty: link'

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

mono]$ numfmt-to=si 1000/mono]

-> "1.0k"

mono]$ numfmt-to=iec 2048/mono]

-> "2.0K"

mono]$ numfmt-to=ie-i 4096/mono]

-> "4.0Ki"

mono]$ echo 1K | numfmt-from=si/mono]

-> "1000"

mono]$ echo 1K | numfmt-from=iec/mono]

-> "1024"

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

 

AUTHOR

Written by Assaf Gordon.  

REPORTING BUGS

Report bugs to: bug-coreutils@gnu.org

Report Gentoo bugs to: https://bugs.gentoo.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/>  

SEE ALSO

Full documentation <https://www.gnu.org/software/coreutils/numfmt>
or available locally via: info aq(coreutils) numfmt invocationaq

Packaged by Gentoo (9.10 (p0))
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.

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Index

NAME

SYNOPSIS

DESCRIPTION

UNIT options:

FIELDS supports cut(1) style field ranges:

EXAMPLES

AUTHOR

REPORTING BUGS

SEE ALSO