Hi,

my blog reader has a question and I’m going to repro his scenario step by step, and answer the question using MS PROJECT 2016.

First I will create a 5 day Task:

There are 2 resources assigned to the project –  John and Mary:

Mary is supposed to work on a week  to 4-day 10hrs/week  schedule, so I customize her personal calendar:

and:

So Mary is supposed to work 10 hours per day from Monday to Thursday, but she is off at Friday. Now I will assign Mary to the Task:

As you can see, Duration is 5 days, even Mary is not working at Friday. How is it so?

Let see here:

and:

and then:

As you can see 1 day of Duration is 8 hours! (see hours per Day option in the picture above).

So for Mary, Total work is 40 hours (10 at Monday, 10 at Tuesday, 10 at Wednesday, and 10 at Thursday). Duration of the Task is 40 hours (Total) / 8 hours per day = 5 days.

Now I will  add John to the Task, and he is “regular” worker, so he is suppose to work 8 hours per day from Monday to Friday:

The question from my Blog reader is: “How Project calculates the new 6-day Duration for the task?”

And the Answer is easy. When only Mary was assigned to the Task the Task duration wad 5 days. Now John will work 1 day more. As simple as that. He will work at Friday. So those 5 days + 1 days (Friday) is 6 days duration. Or let me explain that day by day:

• Monday to Thursday: John works 8 hours = 1 day. Mary works 10 hours = 10to be worked /8 (hours per day) = 1,25 days. Duration is longest one, so it is 1,25 days
• Friday: John works 8 hours = 1 day. Mary does not work. Duration is, obviously 1 day.
• Total: 1,25 (Monday) + 1,25 (Tuesday) + 1,25 (Wednesday) + + 1,25 (Thursday) + 1 (Friday) = 6 days

Hope this helps.

Regards!