Microsoft KB Archive/101495

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Knowledge Base

PRJ: How Percent Complete Is Calculated for Nested Summary Tasks

Article ID: 101495

Article Last Modified on 1/18/2007


  • Microsoft Project 2000 Standard Edition
  • Microsoft Project 98 Standard Edition
  • Microsoft Project 4.1 Standard Edition
  • Microsoft Project 4.1a
  • Microsoft Project 3.0 Standard Edition
  • Microsoft Project 3.0a
  • Microsoft Project 4.0 Standard Edition

This article was previously published under Q101495


Microsoft Project calculates the Summary Level Percent Complete value based on its immediate subordinate tasks (summary and detail tasks). This method of calculation can cause the percent complete for a higher-level summary task to differ from a calculation done by hand if only the detail tasks and not the subordinate Summary tasks are used.

The Percent Complete for a Summary Task is a weighted average of its immediate subordinates.


In order for Microsoft Project to speed up calculations, the percent complete of a summary task is based on its direct subordinate tasks and subordinate summary tasks percent complete (if any).

Project uses the following calculation:

   Percent Complete = Actual Duration / Duration

For a summary task, percent complete is first calculated from its immediate subordinates, and then actual duration is determined. For a task, either percent complete or actual duration can be solved.

The following example assumes a default base calendar with no resource assignments:

   Name             Outline   Dur   Sch St   Sch Fin  %Comp   Act Dur

Top Summary           1       8d    1/1/96    1/10/96   23%    1.8d
Subordinate Summary   1.1     5d    1/1/96    1/5/96    25%    1.25d
   task1              1.1.1   1d    1/1/96    1/1/96    50%    0.5d
   task2              1.1.2   1d    1/5/96    1/5/96     0%      0d
 task3                1.2     1d    1/10/96   1/10/96   10%    0.1d

NOTE: In Microsoft Project 98/2000, the Percent Complete is 20% instead of 23% and Actual Duration is 1.6d instead of 1.8d.

Percent Complete of the "Subordinate Summary" is calculated like this:

   (1d*50%+1d*0%)/2d=25% [(task1 dur) * (task1 %Comp) + (task2 dur) *
   (task2 %Comp)] / [(task1 dur) + (task2 dur)]

Percent Complete of the "Top Summary" is calculated like this:

   (5d*25%+1d*10%)/6d=22.5% (=23%) [(Subordinate Summary dur) *
   (Subordinate Summary %Comp) + (task3 dur) * (task3 %Comp)] / 
   [(Subordinate Summary dur) + (task3 dur)]

Because the duration of the "Subordinate Summary" does not equal the duration of its subordinate tasks, the percent complete of the "Top Summary" task does not reflect the percent complete values of the tasks themselves.

If the Percent Complete of the "Top Summary" was based on only the subordinate tasks, and not the "Subordinate Summary," it would be calculated as follows:

   (1d*50%+1d*0%+1d*10%)/3d=20% [(task1 dur) * (task1 %Comp) + (task2
   dur) * (task2 %Comp) + (task3 dur) * (task3 %Comp)] / [(task1 dur)
   + (task2 dur) + (task3 dur)]

Additional query words: prj2000 3.00a %Complete % Complete

Keywords: kbhowto kbusage KB101495