Free float

Free float in network diagrams such as CPM (Critical Path Method) and PERT (Program Evaluation and Review Technique), is a measure of the amount of time a task can be delayed without delaying the completion of the project or the start of a successor task. It is calculated by subtracting the earliest start time of a successor task from the latest completion time of the current task. Free float is used to identify the critical path of a project, which is the sequence of tasks that must be completed on time in order for the project to be completed on schedule. Tasks with zero or negative free float are considered critical and must be closely monitored to ensure they are completed on time.

Free float vs. Total float

Free float and total float are both measures used in network diagrams such as CPM (Critical Path Method) and PERT (Program Evaluation and Review Technique) to evaluate the schedule flexibility of tasks in a project.

Free float is the amount of time a task can be delayed without delaying the completion of the project or the start of a successor task. It is calculated by subtracting the earliest start time of a successor task from the latest completion time of the current task. Tasks with zero or negative free float are considered critical and must be completed on time to keep the project on schedule.

Total float, also known as slack, is the amount of time a task can be delayed without delaying the completion of the project. It is calculated by subtracting the earliest start time of a task from the latest completion time of the same task. Total float represents the total amount of schedule flexibility available for a task and can be distributed among various tasks in a project as per the project manager's discretion.

In summary, free float is the amount of flexibility a task has without affecting the immediate successor task, while total float is the amount of flexibility a task has without affecting the overall project completion date.

Free float — recommended articles

Baseline schedule — Schedule variance — Total float — Planned value — Critical path method — Critical activities — Project schedule — Earned value calculation — Life cycle project management

References

• Baars, W., Harmsen, H., Kramer, R., Sesink, L., & van Zundert, J. (2006). Project management handbook. Data Archiving and Networked Services, The Hague.
• Kuster, J. (2015). Project management handbook. Springer-Verlag Berlin Heidelberg.
• Hyttinen, K. (2017). Project management handbook. Laurea Julkaisut 76.