How to show a "weeks until" master date?

[Kelly_Appenzell]

I am making a project timeline and I would like to have a function tell me how many weeks out a task is due in relation to a final project date. For example, the event is December 15th. If I added a task due October 15th, the formula would say 8 weeks out.

[Elias_Gomez_Sai]

You’ve got DATETIME_DIFF() function:

Airtable - Support

Formula field reference

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[Kelly_Appenzell]

Yes, but when I try to put in the master date it returns incorrect values. For example.

DATETIME_DIFF({Start Date},04-05-2019,‘weeks’)

How do I use the master date of 04-05-2019

[Kelly_Appenzell]

Nevermind - I figured it out with a work around. I made a Fx field = “04/05/2019” so it auto-filled. Then I hid that column. But the wrote the formula as a to,from that auto-filled date .