Linux ls Command Sort Files By Size

The default output (sort by alphabetically)

Type the following command:
$ ls
$ ls *.py
$ ls *.avi

Fig.01: ls Command Output

Linux force sort by size option

You need to pass the -S or --sort=size option as follows to Linux or Unix command line:
$ ls -S
$ ls -S -l
$ ls --sort=size -l
$ ls --sort=size *.avi
$ ls -S -l *.avi
Sample outputs:

Fig.02: Sort files / folders (directories) by size

You will see largest file first before sorting the operands in lexicographical order. The following command will sort file size in reverse order:
$ ls -l -S | sort -k 5 -n
OR try (see comments below, thanks!):
$ ls -lSr

Fig.03: Ls Command Sort By Size in Reverse (Lowest First) Order

Sort output and print sizes in human readable format (e.g., 1K 234M 2G)

Pass the -h option to the ls command as follows:
$ ls -lSh
$ ls -l -S -h *.avi
$ ls -l -S -h ~/Downloads/*.mp4 | more

Sorting ls command output by file size on Linux

Run the following ls command:
ls -Slh
OR
ls -Slhr

ls Command Sort Files By Size Command Options

How to exclude directories when all files ordered by size

Try filtering outputs of ls command using grep command:
ls -lS | grep -v '^d'
ls -Slh | grep -v '^d'
ls -Slhr | grep -v '^d'

total 289836
-rw-rw-r--.  1 vivek vivek 295599646 Jun  9  2018 lnxpcs-master.zip
-rw-rw-r--.  1 vivek vivek    501221 Dec 27 15:49 top.cvs
-rw-r--r--.  1 vivek vivek    270466 Jan 30  2018 out
-rw-------.  1 vivek vivek    124866 Aug 13 12:38 Receipt Details.pdf
-rwxr-xr-x.  1 vivek vivek     47441 Nov 18  2017 speedtest-cli
-rw-r--r--.  1 vivek vivek     19419 Feb  9  2018 final.txt
-rw-r--r--.  1 vivek vivek     13654 Jan 13 17:09 updated.txt
-rw-r--r--.  1 vivek vivek      8247 Aug 14 09:23 nixcraft.conf
-rw-r--r--.  1 vivek vivek      5083 Jan  8 00:58 wanted.txt
-rw-r--r--.  1 vivek vivek      2674 Jan  3 02:47 vpn.config.ovpn
-rw-rw-r--.  1 vivek vivek      1539 Jun  8  2018 email-ids.txt

One can use find command as well along with sort command to just list dir size in sorted order:
find . -type d -ls | sort -n -r
Or just list files and exclude all dirs when sorting:
find . -type f -ls | sort -n -r

1619988315      0 drwxr-xr-x   2  vivek    vivek         164 Dec 20 15:24 ./images/password-change
1619988314      0 drwxr-xr-x   2  vivek    vivek          84 Nov  7 16:26 ./images/dig-not-found
1619988310      0 drwxr-xr-x   2  vivek    vivek         106 Sep 21 00:34 ./pfsense/fw0.nixcraft.lan
1615242013      0 drwxr-xr-x   2  vivek    vivek          83 Jun 19  2018 ./hello-web-app/pdf
1615241993      0 drwxr-xr-x   2  vivek    vivek         156 Feb  8  2018 ./books/ssh/ssh2\ twp\ 3\ formats\ 2018-02-07

Conclusion

This page showed how to list all files ordered by size in Linux or Unix like systems. See ls(1) command man page for more information.