Hi,

Today I am going to explain slack, or float in MS PROJECT 2013.

There are two types of slack in MS PROJECT 2013:

1. Free slack:
   The free slack of an activity is the time this activity can be delayed without impact on the following activity.
2. Total slack:
   The total slack of an activity is the time this activity can be delayed without impact on the finish date of the project.

First, let me show you that on this pictures:

Here is the example:

As you can see, The Critical Path is: Prepare Outline –> Create Slides –> Add Artwork to Slides –> Review & Spell Check. Tasks Crate Artwork, and  Write Speakers Notes are not on the Critical path and they have a Slack!

1. Task Crate Artwork has Free slack = 22 – 12 = 10 days
2. Task Write Speakers Notes has Free slack = 22 – 3 = 19 days

• If Create Artwork Task is late more than 10 days, Task Add Artwork will be late, as well.
• If Write Speakers Notes Task is late more than 19 days, Task Add Artwork will be late, as well.

Now I am going to put those Tasks into MS PROJECT 2013.

As you can see, My Project will take 25 days!

Now I will apply Detail Gant View:

and then:

and I will get (I will show two pictures because it doesn’t fit on the screen):

and:

You can see that Tasks  Create artwork, and Write Speakers Notes are not on the Critical path and you can see their Free Slack (10 an 19 days)!

Now I will add two new field in my Detail Gant View: Free slack, and Total Slack:

As you can see my calculation is correct.

Slack can be positive, zero, or negative!

Total slack can be different from free slack, of course!

Do you want an example? Read my next post!

Regards,