numfmt — Convert numbers from/to human-readable strings

Examples (TL;DR)


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


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

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


print warnings about invalid input

-d, --delimiter=X

use X instead of whitespace for field delimiter


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


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


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


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


use locale-defined grouping of digits, e.g. 1,000,000 (which means it has no effect in the C/POSIX locale)


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


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


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


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


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


auto-scale output numbers to UNITs; see UNIT below


the output unit size (instead of the default 1)

-z, --zero-terminated

line delimiter is NUL, not newline


display this help and exit


output version information and exit

UNIT options


no auto-scaling is done; suffixes will trigger an error


accept optional single/two letter suffix:

1K = 1000, 1Ki = 1024, 1M = 1000000, 1Mi = 1048576,


accept optional single letter suffix:

1K = 1000, 1M = 1000000, ...


accept optional single letter suffix:

1K = 1024, 1M = 1048576, ...


accept optional two-letter suffix:

1Ki = 1024, 1Mi = 1048576, ...

FIELDS supports cut(1) style field ranges


N'th field, counted from 1


from N'th field, to end of line


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


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.


$ 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


Written by Assaf Gordon.

Reporting Bugs

GNU coreutils online help: <>
Report any translation bugs to <>

See Also

Full documentation <>
or available locally via: info '(coreutils) numfmt invocation'


October 2019 GNU coreutils 8.31