Calculated date not an option for Gantt Chart

[superdave10]

Brand new to Airtable, so forgive me if this is a dumb question.  I've shamelessly stolen a formula to calculate start and end dates based off a T- or T+ from a specific event.

DATETIME_FORMAT(DATEADD({Calculated End date},{Days Needed to Complete},'days'),'MM/DD/YY')

The dates are calculating just fine, but when I try to add a Gantt view, it doesn't allow me to choose these fields to determine the dates for the Gantt.  What do I need to do to have Airtable recognize the output of this formula as a date?

[djseeds · Accepted solution]

Hi @superdave10, welcome to the community!

The DATETIME_FORMAT function formats its input date as a string, so if you use that function Airtable will not recognize the formula field as a date. Please try using only the DATEADD function, which outputs a Date:

DATEADD({Calculated End date},{Days Needed to Complete},'days') 

[superdave10]

This solved it!  It allowed for me to set as a "date" in the format tab, which wasn't an option before.  Thanks for your help.