Duration calculation is incorrect

Question

I have a project with a task that has a work estimate of 13.5 days

I have assigned two resources to this task, one with 100% commitment and another with 50% commitment to the task

Logically the duration should be 9 days, however I am getting a auto calculated duration of 12 days

Another similar task with exactly same config is showing duration as 18 days.

My settings are default 8 hours a day / 20 days a month.

Can anyone suggest why the duration value is incorrectly calculated ?

I have already spent many hours trying to figure this one out, any help would be highly appreciated.

Thanks

Answer 1

This not how I do it because I always start with an estimate of duration, but I am guessing that this is how you are doing it.

13.5 days of work is 108 hours. It is always better to measure work in hours rather than days.

Make a task.

Have the work column displayed in the table.

Do not input a duration. Allow the default 1 day.

Assign the two resources, using the assign resources dialog, one at 100% (the default) and one at 50%.

The duration will not change.

Duration is 1 day, or to be sure, 8 hours.

Work is 12 hours, which is 1.5 x 8, so ok.

Input 108 hours of work.

Duration is re-calculated as 9 days, so ok.

Does this work?

This is all task type = fixed units, effort driven is off. What's yours?

I don't know what you did to get 12 days or 18 days duration, but anything is possible.

Answer 2

RahulBose_858 --

Using the information you provided, Microsoft Project calculated a Duration value of 9 days for me, as expected.  Here is what I did:

1. For the task in question, I entered an initial Duration value of 13.5 days with no resources assigned.
2. Right-clicked in the Gantt Chart pane and selected the "Show Split" item on the shortcut menu.
3. Selected the task in question in the Gantt Chart pane (top pane).
4. In the Task Form pane (bottom pane), I selected the first resource, entered a Units value of 100% for that resource, and then clicked the OK button.  Microsoft Project calculated 108 hours of Work for that resource.
5. In the Task Form pane, I added a second resource to the task at a Units value of 50%, and clicked the OK button.  Microsoft Project calculated the Duration as 9 days, assigned 72 hours of Work to the first resource, and 36 hours of Work to the second resource.

I believe if you follow these steps, you will get the same result.  Hope this helps.