I define a fixed work task, work is 16 h. I assign a resource Bob to work 100% on this task. The task duration is automatically set to 2 days. Since I figure out Bob won't have full time to spend on this task, I double click on the task to add Alice to the resources. I assign Alice to work 50% time on the task and change Bob from 100% to 50%. When applying the change, duration automatically changes to 2,67 days. Why? Two persons are working on a 16 h fixed work task, each with 50%. Why is there 0,67 days more scheduled than needed?

In case in the same task now I delete all resources and click OK and then insert resources again, now for Bob and Alice I assign 50% availability at the beginning, the calculation is correct. 2 days needed for the task to complete. No other changes were made - just resources deleted and entered again.

When the problem is present and I check the Team planner, I can see that Bob and Alice do not work the whole task duration. Note - the project is fresh, no calendars are used, no special cases.

If anyone can help me to understand, what's going on, I will be very grateful. I'm stuck with a large project where I'm unable to change resource availability and getting correct results.

1 Answer 1


Split your screen to show the task form in the lower pane to understand what is happening with the work. When you assigned Alice at 50% - she did not get assigned 50% of the work - she was assigned one third of the work or 5. hours of work. Bob at that moment was still assigned at 100% so his work is 2/3 or 10.67 hours of work. When you dropped him to 50% he still have 10.67 hours of work and duration increases.

Better bet is to: 1) Remove Alice from the task. Because the task is effort driven - the total amount of work will stay the same - 16 hours of work. Bob's assignment units are still 50% so duration increases to 4 days.

2) Assign Alice at 50% - work will be evenly split - 8 hours each and 2 days duration.

Personally I use the Task form for most of my assignments - it paints a much clearer picture of what is really going on.

  • Thank you for your comment. I understand now what's going on. However, I don't see how this is useful. How can I set that the resources should work based on their availability and the task should end as soon as possible? Meaning all resources should work the entire task duration? Your method with deleting the resource and adding them again works, but it's a time consuming and error prone when fine tuning of the project plan that's not simple is needed. Thank you for your time and help!
    – Ziga
    Commented Feb 17, 2016 at 8:17
  • Sorry but you can't set what you want. When you assign resources to tasks project does the following: a) if you don't specify assignment units - the resource will be assigned at his/her max units. b) If you don't specify work - project will calculate the work based upon task duration * assignment units. c) if you specify work - project will recalculate the duration of the assignment based upon work/assignment units. If multiple resources are assigned - each may finish their assignment based upon that math.
    – JulieS
    Commented Feb 17, 2016 at 15:08
  • I can't comment on "useful". If you want the work to be accomplished as soon a possible assign all resources at 100%.
    – JulieS
    Commented Feb 17, 2016 at 15:12
  • Thank you! Your explanation was very helpful. It seems I have wrong expectations about how the work should be done. BTW, I meant as soon as possible, but with available resources - not that one person stops working on the project sooner, but that both persons work the same duration (in calendar days) with different daily availability.
    – Ziga
    Commented Feb 18, 2016 at 7:55

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.