linux show size of folder contents in ls or some other command

du --max-depth=1 -h should show how much space the folders use

Using the command du:

du -sh .

Note that this takes some time, because it has to scan the directory contents.

du -sh

where s displays a summary of the directory size.
h human readable format

Example:

[root@smsc tmp]# du -sh
219M    .