SharePoint Online Calculated Field Support for Blanks

[GeneOlsen]

=IF([Revised Planned Date]="",PlannedFinishDate,[Revised Planned Date]) is the one working

However,

If Both Revised Planned Date and Planned Finish Date are blank show blank.

Currently shows 12/30/1899 in my output when both are blank.

[#2 · Accepted solution]

This did the trick
=IF(PlannedFinishDate="","",IF([Revised Planned Date]="",PlannedFinishDate,[Revised Planned Date]))

[#3]

@GeneOlsen 

Instead of comparing the date fields with empty string (""), you can also use the ISBLANK() function like: 

=IF(ISBLANK([PlannedFinishDate]),"",IF(ISBLANK([Revised Planned Date]),[PlannedFinishDate],[Revised Planned Date]))

---

Please click Mark as Best Response & Like if my post helped you to solve your issue. This will help others to find the correct solution easily. It also closes the item. If the post was useful in other ways, please consider giving it Like.