How to find out directory size in ubuntu from terminal

Commands like ls -l or df -h show me the file sizes or disk space utilization but none of them show me the size of a directory.

To see the directory size in ubuntu from terminal or command line use the command du as below. 

du -hs /path/to/folder

Where,.  

 -h is for displaying the size in human readable format. Like in MB or GB etc.
-s is for summary.