MS Project Professional Master File Duration less than duration of highest Subproject

Occasional Contributor



Hoping someone can help with this one.


Created a Master Project file to track multiple projects and when I insert the first Subproject ("Finance Department Audit Process"), the Master Project Duration is less than the Subproject summary.


Any suggestions on how I can reconcile this would be greatly appreciated.



Task ModeTask Name% CompleteDurationStartFinish
Auto ScheduledMaster Project55%349 days?2022-01-112023-05-12
Auto ScheduledFinance Department Audit Process55%354 days?2022-01-112023-05-12
Auto Scheduled      22-Audit ABC47%180 days?2022-06-222023-02-23
Task ModeTask Name% CompleteDurationStartFinish
Auto ScheduledProduction Audit Process55%259 days?2022-03-132023-03-02
Auto Scheduled   22-Audit ABC-D55%259 days?2022-03-132023-03-02
7 Replies

Thanks for the picture but it doesn't give quite enough information. For example, what is the task ID for each of the tasks shown in your "screen shot"?

Other relevant information:
1. What is the Project calendar for the master?
2. What is the Project calendar for each subproject?
3. If calendars are different, what are the differences (e.g. working hours, working days, hours per day, etc.)?
4. In the master do you have the calculation option set to "on"?
5. Also in your Project options do you have "inserted projects to be calculated like summary tasks"?


@John-project Hi and thanks for the reply.  The calendars for the master and sub projects are all standard M-F 40hr work week however in one of the sub projects there are a number of exceptions where a task start and completion date was on a non working day.  I believe this might be the issue.  Any recommendations to resolve?

Thanks, Ken

Thanks for answering a few questions but you still didn't answer the main question, namely, what is the task ID for each of the lines shown in your "screen shot"?

I'd also like to see the Start and Finish fields for all the tasks shown. As far as the subproject with calendar exceptions I can't offer any recommendations until I see more.


Hi and thanks for your patience.  My project that I was working on was fairly advanced with a lot of content, so it was a bit difficult to get that info. 


I however reproduced the issue in a simpler test project below:


The discrepancy occurred when, for SubProject ABC, I put the start, end completion date on Sunday (non-working day) where I introduced this exception.


The calendars for the Master and subprojects are all Standard (40hrs, M-F).


I hope this is enough info to help diagnose a resolution.  Thanks, Ken


Task ModeTask Name% CompleteDurationStartFinishID
Auto ScheduledMaster Project Test47%62 days?2022-09-232022-12-190
Auto Scheduled   SubProject ABC69%63 days2022-09-232022-12-192
Auto Scheduled      Define Scope100%21 days2022-09-232022-10-211
Auto Scheduled      Development100%5 days2022-10-242022-10-282
Auto Scheduled      Test100%1 day2022-10-302022-10-303
Auto Scheduled      Implement0%12 days2022-12-022022-12-194
Auto Scheduled   SubProject DEF0%29 days?2022-11-092022-12-194
Auto Scheduled      Define Scope0%8 days2022-11-092022-11-181
Auto Scheduled      Development0%15 days2022-11-212022-12-092
Auto Scheduled      Test0%1 day?2022-12-122022-12-123
Auto Scheduled      Implement0%5 days2022-12-132022-12-194
best response confirmed by KenPb (Occasional Contributor)
Yeah that gave me just enough info. Indeed if subproject ABC has exceptions which allow Sunday to be working time then you will see an apparent discrepancy in the Duration field. The master file has the Standard calendar so it is measuring duration time per that calendar which means it will not count Sundays.

It's not clear what you are trying to achieve. You can create a custom Text field with the following formula and it will display the same duration as subproject ABC but only for the case where subproject ABC is the dominant subproject (i.e. starts earlier and finishes later than any other subproject). Why? Because the formula simply measures calendar time instead of working time.
Text1=DateDiff("d",[Start],[Finish]) & " days".
If another subproject has an earlier start or a later finish, then the formula will give an invalid duration. So again, I'm not sure what you are trying to achieve.

Is there a way to create a custom duration at master level that will respond to the intent regardless of whether the subproject with the exceptions is dominant or not? Yes, but it would require VBA.

@John-project Thank you so much for all the help.  With the Master Project file summary line, I was hoping to show the Total number of days based on the dominant subproject (longest duration + exceptions) across all subprojects.  Since I am not VBA savvy, I think I can manage it "manually" with your suggested custom text field.  Once again, thanks for all your help in furthering my understand.

Best regards, Ken

You're welcome and thanks for the feedback. If I answered your question, please consider marking one of my responses as the answer.