What is Float in Project Management?

In project management, float (also called slack) refers to the amount of flexibility a task has in the schedule before it impacts other tasks or the project’s overall completion date. It’s a way of understanding how much “wiggle room” exists in your plan so that unexpected delays don’t immediately derail the entire project.

There are two main types of float: total float and free float.

Total float is the amount of time a task can be delayed without pushing back the project’s final deadline. This is what project managers usually mean when they talk about float.
Free float is the time a task can be delayed without affecting the start of the next dependent task. While it provides some flexibility, it’s more limited than total float since it only accounts for immediate dependencies.

Understanding float is especially useful when managing complex projects with multiple dependencies. By identifying which tasks have float, project managers can prioritize critical path tasks—the ones with no flexibility—while knowing which activities can absorb a delay without major consequences.

Using float wisely helps teams adjust schedules, allocate resources more efficiently, and reduce unnecessary stress when small setbacks occur. However, if delays extend beyond the available float, the project timeline will be directly affected.