Hi,

I’ve got a question form one of my Blog readers:

“Hi Nenad,
Based on the example in your previous post please answer the following questions:
1) When you manually updated the actual work in each of the 3 days for Resource in Task to 4, 12 and 20 hrs, Project calculated actual duration as 3 days. As the default is that one working day is 8h, how did Project calculate the Actual Duration to be 3 days instead of 4+12+20 =36h/8h = 4,5d ?

2) How in this case does Project uses the scheduling formula Work = Duration * Units to calculate the total task Duration of 5.5 days?”

OK. I’ll show you that in MS PROJECT 2016!

I will first create a Project with one Task, 7 days Duration:

I am also going to create John as Resource:

Finally, I’m going to assign John to the Task:

Now I am going to Switch the View to Task Usage, and I’m going to add Actual Duration to it:

On the right size of this View, I’m going to show Actual Work field:

and I will get:

I will put in Actual Work:

• 4 hours for Monday
• 12 Hours for Tuesday
• 20 Hours for Wednesday

and I will get:

As you can see there is a special mark on the Right side of the Task:

Now, why is Actual Duration 3 Days instead of 36/8 = 4,5 days? 36 hours were spent to the Task, that is true. Default is 8 hours per day. That is also true. And 36/8 = 4,5. BUT! Once when you decide to put Actual work manually, formula work=Duration * Unit) will not work any more for this specific Task. Why? Because you can put any value in Actual work. So, Microsoft Project does not use formula any more. Instead it recognized that has been some (ANY) Actual Work in Monday, Tuesday and Wednesday, and no matter how much work was spend it says that Actual Duration is 3 days! That is it!

And what about Duration field? It is now 5,5 days. Here Microsoft Project use formula, but partially. Here is explanation how:

1. Actual Duration is 3 days
2. At Thursday and Friday, John is supposed to work 8 hours per day. It is 2 days!
3. At next Monday, John is supposed to work 4 hours. It is 0,5 days
4. Total is 3 days (Actual) + 2 days (Thursday and Friday) + 0,5 day (Monday) = 5,5 days

To conclude, if you are going to manually put Actual work to the Task, be very careful.

Best Regards!