## Resource Calendar vs. Units in Microsoft Project 2016

Hi,

I’ve got a very good question from one of my blog Readers:

Could you please help me with a question on resource calendar?
If a resource is part time only work 3 days a week. I need to assign this resource 1 day for Task 1, and 2 days for Task 2. What is the best way to set in MSP? Shall I set maximum unit 100% and then use resource calendar to adjust the part time 3 days or Shall I set the maximum unit 60% and then use Task calendar to adjust the allocation?”

Well, when we are talking about Units and Resource Calendar, we are talking about two totally different things.

Let me show you a difference in MS PROJECT 2016!

First,  I will create very simple Project with two Tasks:

Then, I will create two Resources:

As you can see, I told Microsoft Project that John will have 60% maximal units on this Project.

Now, I am going to modify Mary’s Calendar, and I will say that she will work only 3 days per week, but still with 100% units:

As you can see, Mary is not going to work on Thursday and Friday.

Now I will assign John to Task 1, and Mary to Task 2:

Now, I’m going to explain the difference.

Since John is going to work 60%, and we all know magic formula: Work = Duration * Units, and default Task Type for Task 1 is Fixed Units, we will have:

Work = 5 days (8 hours per day) Duration * 60% Units = 5 * 8 * 60% = 24 hours. And John will work 60% per day e.g. 8 hours * 60% = 4,8 hours per day!

Mary, on the other hand will work 100% per day (e.g. 8 hours per day), but she will not work at Thursdays and Fridays, so to finish Task 2, which is 5 days long, she has to work 40 hours (Work = Duration * Units, e.g. Work = 5 days (8 hours per day) * 100% Units = 5*8* 100% = 40 hours!). She will work 5 days and 8 hours per day on her working days, and that means that she has to work From Monday to Wednesday (3 working days) and then Monday and Tuesday next week, to accomplish her Task.

To conclude. % Units is how many hours can Resource work maximum per day (without over allocation), and resource Calendar determine which day will someone work (and when), and which not.

So there is a huge difference.

Final example. Let’s say that John will not work at Thursdays and Fridays (same as Mary). I will modify his calendar (I’m not going to show you screenshots because I showed you already how to do that in Mary’s case), and I will get:

You can see that John and Mary will work same Days (From Monday to Wednesday, and then Monday and Tuesday next week) but since John is only 60% allocated to this Task, he will work 4,8 hours per day which is 24 hours in Total.

Hope this helps!

Regards