Datediff

[Craigsquestions]

Good day, 

I'm using project desktop. I used the the date diff formula to calculate the days left from now until the finish date of a task, but I want to know is there a way to use this formula or any other method to calculate/show the amount of days between 2 specific tasks. They are not direct predecessors.

Thanks in advance

[#2]

Craig --

No, there is no way to write a formula in Microsoft Project that will calculate the amount of days between two tasks. Sorry, but hope this helps.

[#3]

Craigsquestions,
Yes, but you can't do it with a custom field formula since that formula can only reference data on a single task line.

However, with VBA, virtually anything can be done. If you can supply more details (e.g. how the 2 specific tasks are determined, are you looking for working days or calendar days, etc.), I can write some code for you.

John

[#4]

@Craigsquestions 

I can offer the following "impractical" approach. Suppose that you need to constantly watch the days between T1's finish and T3's start.

Flag1 renamed as Mark_Finish, Flag2 renamed as Mark_Start

Finish1's formula: iif( [Flag1], [Finish], ProjDateValue("NA"))
Select "Rollup: Maximum" for summary rows

Start1's formula: iif( [Flag2], [Start], ProjDateValue("NA"))
Select "Rollup: Maximum" for summary rows

Number1's formula: iif( [ID] = 0, ProjDateDiff( [Finish1], [Start1] ) / [Minutes Per Day], 0)
Select "Use Formula" for summary rows

And this is the result:

You can hide the columns for Finish1 and Start1, after having done with testing.