Count Hours between 2 dates

Hello Forum,

I'm trying to add a column that gives me the hours between 2 dates/times.

From what I've searched i found how to count weekdays from a start and end hour, how to count if the weekend days are on other days, but I cant find for my problem.

I need to count the hours occurred between 09AM and 09PM (12h/7days).
Example:
01/01/2019 09:30 > 02/01/2019 10:00 = 12:30H


Thanks