Hi all. 
If I set the Start and End data of a task, there currently is no way to know how many days that is.  (Duration)

I know I can set Estimated time but it isn't the same thing.

Is there any way to see a Task's duration?  Ideally I'd like to see it in its own column.

Hello, 

Thank you very much for your question. We currently have a feature request for adding a duration column to work packages. 
I have added your vote. 

Have a great day!

Kind regards
Samantha