I'm a little confused about how MS Project 2007 is calculating % Complete in the following instance....

As you can see, CM Front Office (Level 1) is showing 99% Complete, even though there are numerous tasks that have yet to be started, and showing 0%. There are actually even more incomplete tasks that are not captured in this screenshot.

I understand the formula for % Complete = Actual Duration / Duration. I forgot to show the Duration columns, but I don't think Actual Duration is calculating correctly...

Thanks in advance for reading and helping me out!

Percentage Complete Mystery


@Tobias & Haotian,

A summary task is not 100% complete until all of its subtasks (even milestones) are 100% complete.

When the milestones are widely spread (as your example) the span between the milestones is not counted as duration. Although task 140 spans from end of February to early July unless there are additional tasks with duration > 0, the % complete will always be 99% complete.

Although your formula is accurate for subtasks - summary task % complete is not as straight forward. See:https://support.microsoft.com/en-us/kb/101495 for a detailed discussion, but in brief it is a "weighted" percent complete based upon the duration of the subtasks. Although the article references much older releases of Project, I believe the same concepts hold for current releases.

  • Thanks for the answer! Just wondering why it's at 99% as opposed to say 60% which would be more representative?
    – Haotian
    May 5 '15 at 16:12
  • What is the status date of this schedule? May 5 '15 at 17:33
  • Hi David, the status date is set to 4/30.
    – Haotian
    May 6 '15 at 16:25

JulieS has the best answer for how Project calculates the % complete for summary tasks, but if you're Gantt chart shows progress based on % complete the results are likely misleading.

My Gantt charts show summary task progress based on the Summary Progress field. This field accounts for when subtasks are scheduled. If none of the subtasks are behind the summary roll-up will also show that things are on-track. How to set up Summary Progress


Assuming that your question is something like:

Why does MS Project behave like this, if my formula is correct?

Here is my answer:

Most of your tasks have duration 0 (= milestones). Those are not taken into account (resp. with 0).

As far I could see, there is just one task with an "real" duration and this one is completed. The (new) question is: Why is the overall % not at 100% :)


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