Calculating times, duration and dates

This is a wiki page. Be bold and improve it!

If you have any questions about the content on this page, don't hesitate to open a new ticket and we'll do our best to assist you.

Online time calculator:
http://www.grun1.com/utils/timeCalc.html

This thread includes a python script to calculate times:
https://ubuntuforums.org/showthread.php?t=1581039

Another solution would be with libreoffice, using a spread sheet.