The slack in an activity’s schedule: how much it can be delayed without consequence. 0 for every activity on the critical path.
Total Float
Total float=LFTend−ESTstart−duration
How much an activity can be delayed without delaying the project’s completion. Delaying it by more than its total float may still delay other activities.
Free Float
Free float=ESTend−ESTstart−duration
How much an activity can be delayed without delaying the earliest start of any following activity.
Independent Float
Independent float=ESTend−LFTstart−duration
How much an activity can be delayed without affecting any preceding or following activity’s float. Negative values are treated as 0.
Independent float≤Free float≤Total float