Please upload a Tableau Packaged Workbook including sample data for specific advice.
General advice - Take a look at the datediff function here https://onlinehelp.tableau.com/current/pro/desktop/en-us/functions_functions_date.html
Thanks for providing the link. But the data source is Power Pivot (Cube) and I want to create a Calculated Member that calculates the duration (day) from today to any future dates. Thanks
Please refer the below link which answers the similar qns about finding number of Working days. In your case you may need to use today() and Scheduled End Date and following the logic explained for calculating only working days.
Hope this helps. If you find the solution helpful, please mark the answer as needed.
The data source is from Power Pivot (Cube), So the links provided doesn't work. I am trying to create Calculated member for cube data source, not a calculated field. I hope the question is clear now. Thanks for the info though.
Here's how you create a calculated member - How to Create a Calculated Member
It sounds like your problem is more to do with what your MDX formula should be - if that's true, the Tableau forum might not be the best place for you to get such help.
With that being said, you can search the forum and you'll see a bunch of advice regarding MDX formulas in Tableau and using date functions -