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

In Primavera P6, there are two key scheduling concepts: Total Float and Free Float. While they may seem similar, they serve different purposes.

• Total Float:
  The amount of time an activity can be delayed without delaying the project’s finish date.
• Free Float:
  The amount of time an activity can be delayed without delaying the start of its immediate successor.

Let’s consider a sample project network:

• Activities A, B, C, D, E, I have a Total Float of 0 days.
  → Any delay in these activities will directly delay the Project Finish Date.
• Activities F, G, H have a Total Float of 5 days.
  → These activities can be delayed by up to 5 days without affecting the Project Finish Date.
• Activity A has a Free Float of 0 days.
  → A delay in Activity A will delay its successors (Activities B and F).
• Activity H has a Free Float of 5 days.
  → It can be delayed by 5 days without delaying its successor (Activity I).

Key Insights

Here are some useful tips to understand the relationship between Total Float and Free Float:

1. If Total Float = 0, then Free Float is also 0.
   → The activity is critical to both the Project Finish Date and its successor.
2. If Free Float = 0, Total Float may or may not be 0.
   → The activity is critical to its successor, but it might still have some flexibility in the overall project timeline.