Changing subtask durations proportionally to summary task duration RRS feed

  • Question

  • Is there a way to change task durations automatically based on changes to a summary task (or if there's a better way to set it up, I'm open to other options)?

    For example, if I have a summary task that runs 60 days and two linked subtasks under it at 30 days each, and then I change the summary task duration to 30, I'd want the two subtasks to update to 15.

    Just looking to find out if this is possible, or if I can accomplish something similar through a different method.


    Thursday, November 12, 2015 3:29 PM

All replies

  • Dude Guy,

    No. You misunderstand the definition of a summary "task". A summary line is not a task at all but rather a summary of the subtasks under it. In versions of Project prior to Project 2010 a user could not change the Duration field of a summary task, as it was a non-editable field. In Project 2010 and later, the user can change the Duration field of a summary task but then that summary task becomes a manually scheduled task.

    Tasks under a summary line represent descriptions of effort to be accomplished. Therefore the best way to edit or update the schedule is to status the data of those tasks.


    Thursday, November 12, 2015 3:47 PM
  • Okay, that's fine, I realize that's not how the summary task usually works but I thought maybe I was missing a setting that could make it work that way. I don't really care what the specific method is, what I'm looking to do is to proportionally change the duration (either up or down) of a number of linked tasks by changing the start/finish of one or two items.

    I'm not a heavy user of Project so this may not be a standard use case. Maybe it's not possible. But even if it's accomplished through subprojects, links between projects, or anything like that, it would work.

    • Edited by Dude Guy Thursday, November 12, 2015 4:11 PM
    Thursday, November 12, 2015 4:07 PM
  • Dude Guy,

    To be honest, it's hard to imagine a realistic schedule wherein task durations would be changed en masse. Remember that in Project the duration is the time during which a task will be performed. It is different than work, which is the effort needed to perform that task.

    Project has a basic work equation which is:

    Duration = Work/Units

    Normally, either the work or resource assignment (units) are modified as the plan is developed or executed depending on expected or actual outcome. Project then adjusts the duration accordingly.

    If you are a casual user of Project I strongly recommend against attempting to create subprojects with a master, or links between projects. Lnked structures in Project are fragile and a very prone to file corruption. Making that structure work successfully requires experience and discipline.

    What is your end goal? If we could understand your larger picture, perhaps we could suggest an approach. Note that one approach might be to do what you need in Excel and not try to force Project to do something is was not designed to do (square peg, round hole thing).


    Thursday, November 12, 2015 4:25 PM
  • Thanks for the responses... I did end up using Excel. I thought it would be nice to have the gannt chart picture but Excel did the trick just fine.

    The overall goal was to see how contractors would fit into a bunch of related subprojects, and what made the most sense for the length of contracts.

    Thursday, November 12, 2015 6:20 PM
  • Dude Guy,

    You're welcome and it sounds like you found a solution via Excel. I'm not saying you couldn't use Project to help with what you are doing but without more details, we really can't be of much help.


    Thursday, November 12, 2015 9:12 PM