Broken roll-up calculation when using hour durations for sub-tasks?


I have a parent task called Foo and two sub-tasks, Bar and Bie. When I enter 1h as the duration for both sub-tasks, the roll-up duration calculation for Foo shows 1.125d. I'm actually seeing this throughout my sheet with another instance having 4 sub-tasks add up to 5h but the parent shows 0.375d. I've made sure the length of day is set to 8 in the project settings. Any idea how I can get accurate parent task durations?


  • AravindGP
    AravindGP ✭✭✭✭✭✭

    Hi @smartsnewb

    It might help if you can share a screenshot. I have tried to replicate your scenario and it shows up correctly when predecessors are added (image 1) and the overall time will differ when it is not (image 2).


    Aravind GP| Principal Consultant

    Atturra Data & Integration

    M: +61493337445


  • smartsnewb

    Thanks for trying to repro, Aravind. As you can see below, when not using predecessors, I get odd outcomes like task Eight showing 1.25d even though Eleven is the last of the sub-items and they add up to 0.5d... I get that adding predecessors would/does make Eight show 0.5d, but where does 1.25d come from? And why is Test showing 1.25d.

    Also, when I add predecessors to some earlier tasks, it does change the rollup to an accurate number... 1.75d

    ...but then if I remove those predecessors... it changes to 1.5d instead of going back to 1.25d

  • Paul Newcome
    Paul Newcome ✭✭✭✭✭✭

    It looks right to me.

    Without predecessors, we can see that there is at least one full day because your end date is the day after the start date. That means a minimum of one day. Then the second day has no duration more than 2 hours which is a quarter (0.25) of a workday (8 hours).

    When you add the predecessors, you indicate that certain tasks have to be completed before others can be started. This means now your hours are in series as opposed to stacked on top of each other and happening at the same time.