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Is there a standard tool which converts an integer count of Bytes into a human-readable count of the largest possible unit-size, while keeping the numeric value between 1.00 and 1023.99 ?

I have my own bash/awk script, but I am looking for a standard tool, which is found on many/most distros... something more generally available, and ideally has simple command line args, and/or can accept piped input.

Here are some examples of the type of output I am looking for.

    1    Byt  
  173.00 KiB  
   46.57 MiB  
    1.84 GiB  
   29.23 GiB  
  265.72 GiB  
    1.63 TiB  

Here is the bytes-human script (used for the above output)

awk -v pfix="$1" -v sfix="$2" 'BEGIN { 
      split( "Byt KiB MiB GiB TiB PiB", unit )
      uix = uct = length( unit )
      for( i=1; i<=uct; i++ ) val[i] = (2**(10*(i-1)))-1
   }{ if( int($1) == 0 ) uix = 1; else while( $1 < val[uix]+1 ) uix--
      num = $1 / (val[uix]+1)
      if( uix==1 ) n = "%5d   "; else n = "%8.2f"
      printf( "%s"n" %s%s\n", pfix, num, unit[uix], sfix ) 

Update  Here is a modified version of Gilles' script, as described in a comment to his answer ..(modified to suit my preferred look).

awk 'function human(x) {
         s=" B   KiB MiB GiB TiB EiB PiB YiB ZiB"
         while (x>=1024 && length(s)>1) 
               {x/=1024; s=substr(s,5)}
         xf=(s==" B  ")?"%5d   ":"%8.2f"
         return sprintf( xf"%s\n", x, s)
      {gsub(/^[0-9]+/, human($1)); print}'
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It looks like here we have a new standard tool in the making :) –  Gowtham Jul 26 '12 at 18:57

7 Answers 7

up vote 10 down vote accepted

No, there is no such standard tool.

Since GNU coreutils 8.21 (Feb 2013, so not yet present in all distributions), on non-embedded Linux and Cygwin, you can use numfmt. It doesn't produce exactly the same output format (as of coreutils 8.23, I don't think you can get 2 digits after the decimal points).

$ numfmt --to=iec-i --suffix=B --padding=7 1 177152 48832200 1975684956

Many older GNU tools can produce this format and GNU sort can sort numbers with units since coreutils 7.5 (Aug 2009, so present on modern non-embedded Linux distributions).

I find your code a bit convoluted. Here's a cleaner awk version (the output format isn't exactly identical):

awk '
    function human(x) {
        while (x>=1000 && length(s)>1)
            {x/=1024; s=substr(s,2)}
        return int(x+0.5) substr(s,1,1)
    {gsub(/^[0-9]+/, human($1)); print}'

(Reposted from a more specialized question)

share|improve this answer
Okay, thanks. About your script, I basically really like it. There are a few things which caught my attention: (1) var s should be have leading B. Also this string is easily changed to IEC Binary notation. (2) It skips the 1000-1023 range in favour of 1<next size> (easily changed) (3) It does not have decimal values (which I do want). Again this is easily changed. When displaying 2 decimal places, the %f format causes a round-up to the <next size> for values 1019-1023; but it's not worth a workaround ..I've posted a modified version in my answer, for general reference. –  Peter.O Jul 27 '12 at 8:17

As of Feb 2013 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. ‘4G’ ==> ‘4,000,000,000’).

E.g. :

echo 5607598768908 | numfmt --to=iec-i



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

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numfmt is a newly added tool to coreutils package from coreutils-8.21 onwards . –  Zama Ques Mar 24 '14 at 10:50

There are a couple of perl modules on CPAN: Format::Human::Bytes and Number::Bytes::Human, the latter one being a bit more complete:

$ echo 100 1000 100000 100000000 |
  perl -M'Number::Bytes::Human format_bytes' -pe 's/\d{3,}/format_bytes($&)/ge'
100 1000 98K 96M

$ echo 100 1000 100000 100000000 |
  perl -M'Number::Bytes::Human format_bytes' -pe 's/\d{3,}/
   format_bytes($&,bs=>1000, round_style => 'round', precision => 2)/ge'
100 1.00k 100k 100M

And the reverse:

$ echo 100 1.00k 100K 100M 1Z |
  perl -M'Number::Bytes::Human parse_bytes' -pe '
100 1024 102400 104857600 1.18059162071741e+21

NOTE: the function parse_bytes() was added in version 0.09 (2013-03-01)

share|improve this answer

This is a complete rewrite inspired by Peter.O's modified version of Gilles' awk script.


  • Fixes Peter.O's bug where he looks for a string of >1 character where he should be looking for one >4 characters. Due to that bug, his code doesn't work for ZiB units.
  • Removes the very ugly hardcoding of a long string of space-separated unit sizes.
  • Adds command line switches to enable/disable padding.
  • Adds command line switches to go from base-1024 (KiB) to base-1000 (KB) notation.
  • Wraps it all in an easy to use function.
  • I place this in the public domain and welcome widespread use.


bytestohuman() {
    # converts a byte count to a human readable format in IEC binary notation (base-1024), rounded to two decimal places for anything larger than a byte. switchable to padded format and base-1000 if desired.
    local L_BYTES="${1:-0}"
    local L_PAD="${2:-no}"
    local L_BASE="${3:-1024}"
    BYTESTOHUMAN_RESULT=$(awk -v bytes="${L_BYTES}" -v pad="${L_PAD}" -v base="${L_BASE}" 'function human(x, pad, base) {

         while (x>=base && length(s)>1)
               {x/=base; s=substr(s,2)}

         xf=(pad=="yes") ? ((s=="B")?"%5d   ":"%8.2f") : ((s=="B")?"%d":"%.2f")
         s=(s!="B") ? (s basesuf) : ((pad=="no") ? s : ((basesuf=="iB")?(s "  "):(s " ")))

         return sprintf( (xf " %s\n"), x, s)
      BEGIN{print human(bytes, pad, base)}')
    return $?

Test Cases (if you want to look at the output):

bytestohuman 1; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 500; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 1023; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 1024; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 1500; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 150000; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 150000000; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 150000000000; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 150000000000000; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 150000000000000000; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 150000000000000000000; echo "${BYTESTOHUMAN_RESULT}.";

bytestohuman 1 no 1000; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 500 no 1000; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 1023 no 1000; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 1024 no 1000; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 1500 no 1000; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 150000 no 1000; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 150000000 no 1000; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 150000000000 no 1000; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 150000000000000 no 1000; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 150000000000000000 no 1000; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 150000000000000000000 no 1000; echo "${BYTESTOHUMAN_RESULT}.";

bytestohuman 1 yes; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 500 yes; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 1023 yes; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 1024 yes; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 1500 yes; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 150000 yes; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 150000000 yes; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 150000000000 yes; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 150000000000000 yes; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 150000000000000000 yes; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 150000000000000000000 yes; echo "${BYTESTOHUMAN_RESULT}.";

bytestohuman 1 yes 1000; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 500 yes 1000; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 1023 yes 1000; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 1024 yes 1000; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 1500 yes 1000; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 150000 yes 1000; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 150000000 yes 1000; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 150000000000 yes 1000; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 150000000000000 yes 1000; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 150000000000000000 yes 1000; echo "${BYTESTOHUMAN_RESULT}.";
bytestohuman 150000000000000000000 yes 1000; echo "${BYTESTOHUMAN_RESULT}.";


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Via linux - Is there a command line calculator for byte calculations? - Stack Overflow, I found about GNU Units - though without examples on the SO page; and as I didn't see it listed here, here is a small note about it.

First, check if the units are present:

$ units --check-verbose |grep byte
doing 'byte'

$ units --check-verbose |grep mega
doing 'megalerg'
doing 'mega'

$ units --check-verbose |grep mebi
doing 'mebi'

Given that they are, do a conversion - printf format specifiers are accepted to format the numeric result:

$ units --one-line -o "%.15g" '20023450 bytes' 'megabytes'  # also --terse
    * 20.02345
$ units --one-line -o "%.15g" '20023450 bytes' 'mebibytes' 
    * 19.0958499908447
$ units --one-line -o "%.5g" '20023450 bytes' 'mebibytes' 
    * 19.096
share|improve this answer

Short and sweet, shell only solution:

convertB_human() {
for DESIG in Bytes KB MB GB TB PB
   [ $NUMBER -lt 1024 ] && break
   let NUMBER=$NUMBER/1024
printf "%d %s\n" $NUMBER $DESIG

It doesn't show the decimal potion.

The let VAR=expression is Korn-ish. Substitute with VAR=$(( expression )) for Born-again-ish.

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AFAIK there is no such standard tool to which you can pass text and it returns a human readable form. You may be able to find a package to accomplish the said task for your distro.

However, I do not understand why you may need such a tool. Most packages that give a related output, usually have a -h or equivalent switch for human-readable output.

share|improve this answer
For purposes of understanding: Human-readable means just that; readable by humans. The various different units of size shown by the tools you mention are not intended for programatic calculations, for which uniformity of units is essential. Working with bytes, which are always integers, is the only way bash can do any arithmetic with them. So... calculate in Bytes... report to in Human, eg. "You are about to permanently delete 3 files, totalling 2.44 GiB. Continue? –  Peter.O Jul 26 '12 at 16:13
I think this should be part of your question. Looks to me like you've got the problem solved. Good luck. –  shellter Jul 26 '12 at 22:20
A common application is to generate numbers of bytes for sorting, and convert to human-readable units after sorting. –  Gilles Jul 26 '12 at 23:44

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