Free Float is the amount of time that a schedule activity can be delayed without delaying the early start (ES) of any successor activity or violating a schedule constraint. It helps project managers identify flexibility within a schedule while ensuring no impact on dependent tasks.
Key Aspects of Free Float
- Measures Task Flexibility – Determines how much an activity can be delayed without affecting successors.
- Does Not Impact Project Completion – Unlike total float, free float does not delay the overall schedule.
- Useful for Resource Optimization – Helps in reassigning resources without causing timeline issues.
- Relevant in Non-Critical Path Activities – Typically applies to tasks not on the critical path.
Formula for Free Float
Where:
- ES_successor = Early Start of the successor task
- EF_current = Early Finish of the current task
Example Calculation
| Task | Duration | Early Start (ES) | Early Finish (EF) | Successor ES | Free Float (FF) |
|---|---|---|---|---|---|
| A | 4 days | 1 | 4 | 6 | 1 day |
| B | 3 days | 5 | 7 | 8 | 0 days |
- Task A has 1 day of Free Float (since Task B starts at day 6, and Task A finishes at day 4).
- Task B has 0 Free Float (must start immediately after Task A to stay on track).
Mermaid Diagram: Free Float Visualization
graph LR; A["Task A (ES: 1, EF: 4)"] -- Free Float: 1 Day --> B["Task B (ES: 6, EF: 8)"] B --> C["Task C (ES: 9, EF: 12)"]
Why Free Float Matters
- Improves Scheduling Flexibility – Identifies opportunities to adjust timelines.
- Prevents Unnecessary Task Delays – Helps teams prioritize tasks efficiently.
- Enhances Resource Allocation – Frees up resources for other work without impacting schedules.
- Supports Critical Path Analysis – Helps differentiate between float types in scheduling.
See also: Total Float, Critical Path, Near-Critical Activity, Near-Critical Path, Schedule Network Diagram.