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Automatic calculation of lag time

Anna Tezcanli
edited 12/09/19 in Archived 2017 Posts

Hello Smartsheet community!!

I hope someone can help me with the following question:


I have 1 activity that depends on another BUT does not necesarly needs to start right after the predecent activity finish. I know that the duration of the activity is 2 days, and the exact date when it has to be finish. Is there any way to set dependency and the end time so Smartsheet automatically calculate the lag "days" ?


Hmm difficult to explain so tons of thanks for any help.







  • J. Craig Williams
    J. Craig Williams ✭✭✭✭✭✭



    If I understand correctly, you have two conflicting constraints.

    1. Task C can start after Task A is completed.

    2. Task C must finish before a deadline (let's call that Task B)


    You first option is to see Task C's predecessor to Task B as a Finish-to-Finish relationship.

    This means that Task C can't finish before Task B finishes.

    With a 2 day duration, this will show up with a [Start Date] of 2 days before the deadline.


    Then set a Conditional Notification on Task A to send an email to the person responsible for Task C when Task A is finished - letting them know they can start.




  • Anna Tezcanli
    edited 03/27/17

    Hello Craig and thanks a lot for your comment.

    I think I will rephrase my question so it's easier to understand.

    My question is only about 2 tasks, I liked the way you formulated your answer so lets keep calling them A and B.




    1. Task A finishes the 31st of Jan and tasks B depends on tasks A but I want it to start on May 25th.

    2. I know that tasks B only takes 2 days to perform.


    The only way for me to ensure that the Gantt Chart is correct with dependencies between A and B is adding the correct lag days between the 31st of January and May (this I have to count manually).

    Smartsheet only allows me to write the exact number of days between this 2 dates. Is there any way for me to only choose the exact date when I would like task B to start? or do you have any other way to do this?


    I hope my questions i more clear now Laughing


    Kind Regards,






  • J. Craig Williams
    J. Craig Williams ✭✭✭✭✭✭



    In my opinion, you have TWO constraints on Task B.

    1. Task A completed.

    2. Start no earlier than May 25th.


    In some other PM tools, you can set both of those in the constraints for Task B.

    Not in Smartsheet.

    The way I get around this is to add another task (C) with 0 duration and start/end dates of May 25th.

    Task B then points to Task A and Task C.

    If Task A goes past May 25th and the schedule is updated to reflect it, Task B's start date shifts.


    (Note that Task A/B/C no longer match my other post)



  • Anna Tezcanli
    edited 03/28/17

    Interesting workaround. I will try it for sure!

    Thanks a lot Craig for your good advise always really appreciated.


    Have a lovely day,



This discussion has been closed.