# How does Project calculate Actual Duration from manually entered irregular actual work in Timephased sheet • ### Question

• Hello,

Please advise on how does Project calculate a task's Actual Duration after actual work  for resources is entered in the timephased  portion of Task Usage View in such a way that some values of the actual work do not correspond to their assignment units.

In the example below, the original 5 days task has two resources assigned to it at 50% and 100% of their capacity.

After actual work for two resources was entered into the timephased sheet, Project calculated the task's duration of 5.63 days which is perfectly understandable. But how does Project come up wth the Actual Duration of 3.67 days ?

Shouldn't it calculate the task's actual duration similarly to the way it calculates the task's duration? That is,  to count the number of days  the task has actual work and add the portion of the last day's according to the amount of  actual work on that day? In such a case the Actual Duration would be  equal to  4 days, that is , Mon, Tue, Wed and Thu instead of 3.67 days. Where is my mistake in calculations?

Thank you,

Alex • Edited by Wednesday, August 9, 2017 3:18 PM
Wednesday, August 9, 2017 4:48 AM

### All replies

• Alex --

If you read the Help article about the Actual Duration column, you will discover that Microsoft Project calculates this value using the following formula:

Actual Duration = Duration x % Complete

If you do the math, you will see the formula gives you the result you see in the project.  Hope this helps.

Dale A. Howard [MVP]

Wednesday, August 9, 2017 4:49 PM
• Dale,

You are absolutely right, but in order to use this formula you also need to know the %Compete which is also unknown and I don't know how to calculate in this case.

If the actual timephased work in the Task Usage View was not edited the way it was, so it corresponded to resources' assignment units, the Actual Duration for the task could have been calculated easily as Actual Duration = Actual Work /Units or as (Actual Work / Work) * Duration = %Work Complete * Duration = %Complete * Duration.

But in this case when the timephased actual work for resources was edited and does not reflect  their assignment units, those formulas don't work. That's why I would like to get help in explaining of how Project determines the Actual Work value in this case. By knowing Actual Duration all other values can be easily calculated.

Thank you,

Alex

Wednesday, August 9, 2017 9:26 PM
• Alex --

You are going down the wrong path, my friend.  Numbers like Actual Duration and % Complete are not calculated using any Work values.  If you read the Help articles about Actual Duration and % Complete, you can determine the formulas the software uses for calculating these two values.  Hope this helps.

Dale A. Howard [MVP]

Wednesday, August 9, 2017 10:09 PM