# Free Float In | CPM | Primavera P6 | Project Management

### What is Free float In Project Management?

-Free float/slack in CPM (Critical Path Method Calculation) or in Pmbok: is an amount of time that a schedule activity can be delayed without delaying the early start of any following activities.

-Free float(FF) is the amount of time that a schedule activity can be delayed without delaying the early start (ES) date of any immediate successor activity within the network path.

### Free Float Formula in Critical Path Method

Here below the free float formula in CPM calculation:

Free Float Formula 1 = Earliest ES (Early Start) of Following Activities – ES (Early Start) of Present Activity – Duration of Present Activity

Free float Formula 2: is measured by subtracting the early finish (EF) of activity from the early start (ES) of the successor activity.

### Free Float In PMBOK

Now let us look at a different type of Float: It’s the Free Float in Pmbok. PMBOK defines the free float: It’s the amount of time that a time schedule can be delayed without delaying the early start date of immediately following scheduling activities.

This is calculated on the last activity on a path. So the node with Free Float in Pmbok is always the activity right before the finishing activity for Activity on Arrow type of Network Diagram or the finish for Activity on Node type of network diagram.

### How to identify and calculate Free Float/Slack?

Free float is calculated by subtracting the early finish (EF) of the activity from the early start (ES) of the following activity.