The way the % Complete field is calculated depends on the % Complete Calculation Method selected for that project.
Here’s a short description of the three methods:
1. Manual: If this option is selected, the value in the % Complete fields are manually entered at all levels in the task breakdown structure. Entering a % Complete value for a task does not affect any other tasks in the hierarchy. Similarly, the project level % Complete field will also need to be entered manually as it will not be impacted by making any updates to the project tasks.
2. Duration: This method measures the passage of time. If this option is selected, you can manually enter percent complete at the detail task level. However, the summary task and project level percent complete will be read only and will calculate based on the percentage of completed duration of all the detail tasks.
% Complete = Completed Duration / Total Duration
Here is a short example of this one:
A summary task S1 includes detail tasks T1 and T2. The PM manually updates T1 as 10% complete and T2 as 25% complete. Assuming the total duration for T1 is 64 days, at 10% complete, the task is 6.4 days complete. Assuming the total duration for task T2 is 129 days, at 25% complete, this second task is 32.25 days complete.
Using the equation above, the summary task is automatically updated to equal the Completed Detail Task Duration / Total Detail Task Duration.
(6.4 days +32.25 days)/193 days =20%
3. Effort: This method will calculate the percent complete for all tasks. The % Complete on all summary and detail tasks will be read only. When using this method, only work done by labor resources is considered. (All non labor actuals and ETC will be ignored.)
The percent complete will be calculated based on the following formula:
% Complete = Labor Actuals/( Labor Estimates + Labor Actuals)
Where labor actuals is the sum of all actuals posted for labor resources, and labor estimates is the sum of all ETC for these resources.
Percent complete for a summary task is calculated by aggregating the labor resource actuals on the child tasks and dividing it by the sum of the labor resource total effort on all the child tasks.
Percent complete for a detail tasks is calculated by aggregating total labor resource actuals on the task assignments and dividing it by the total effort of all assigned labor resources.
The % Complete calculation at the summary task or project level (for projects using the Effort or Duration calculation methods) can be triggered by some actions such as posting timesheets or autoscheduling the project. Additionally, there is also the ‘Update % Complete’ job that will update the summary and project level % Complete values on these projects. This job can be scheduled to run as often as every 10 minutes.