Hi, Today I will show you relationship between Task Duration, Start and Finish date in Microsoft Project for the Web.

First I will create a simple Project with one Task:

A you can see, Duration Start, and Finish date are empty.

Now let’s say that Duration is 3 days:

As you can see, Start and Finish dates are calculated according to Calendars (which are beyond this Post).

Now Let’s say that I have situation shown in a first picture where all three fields are empty), and I know that Start Date is August 27th:

Duration is calculated as 1 Day, Finish date is calculated according to Calendar (in my case it is same as Start date), and Constraint – Start no earlier than is set for the Start Date:

Now I will repeat steps described above, but this time with Finish Date (I will put August 27th), and I will get:

Start date is Project Start Date (which is in my example – August 24th), and Duration is calculated as 5 Days, and Constraint – Finish no earlier than is set for the Finish Date.

If I remove either Duration, Start or Finish Date, all other two fields will be removed as well.

Now Let’s say that I have a Project with two Tasks:

All three fields are empty for both Tasks. If I choose that Task 2 is predecessor for Task 1, I will get:

Task 1 will start at Project Start Date, and it will have 1 day Duration. Task 2 will also have 1 day Duration. All other Dates (Task 1 Finish date, and Task 2 Start and Finish dates), are going to be calculated according to Calendars.

Finally If I erase Duration, Start or Finish date at any of those two Tasks, the link between them will be lost. For example, I will erase Task 2 Start date, and I will get:

So, be careful when you put or delete Duration, Start or Finish date for Tasks.

Regards.