What is the difference between Total Float and Free Float in Primavera P6

In Primavera P6, there are two important values: Total Float and Free Float.

So what are the differences between them?

• Total Float: is the amount of time an activity can be delayed without delaying the Project Finish Date.
• Free Float: is the amount of time an activity can be delayed without delaying its Successor Activity Finish Date.

Let’s look at the following example:

• The Total Float value of Activity A, B, C, D, E, I is 0 day. Meaning that if they were delayed, the Project Finish Date would have been delayed.
• The Total Float value of Activity F, G, H is 5 days. Meaning that they could be delayed of 5 days without making the Project Finish Date delayed.
• The Free Float value of Activity A is 0 day. Meaning that if it were delayed, the Successor Activity Finish Date (Activity B, F) would have been delayed.
• The Free Float value of Activity H is 5 days. Meaning that it could be delayed of 5 days without making the Successor Activity Finish Date (Activity I) delayed.

There are a few tips, addressing the relationship between Total Float and Free Float, as follows:

• If Total Float value of an activity is zero, definitely the Free Float value of it is zero. Meaning that the activity is critical to Project Finish Date and to its successor.
• If Free Float value of an activity is 0, it’s not certain that the Total Float value of it is 0. Meaning that the activity is critical to its successor, but it may not be critical to Project Finish Date.