The amount of slack in your schedule indicates how long tasks can be delayed before other tasks or the project finish date are affected. The critical path method calculates the early dates (Early Start and Early Finish), late dates (Late Start and Late Finish) and total slack. This technique is used to help project managers to determine the shortest possible project duration and the level of flexibility that exists in the project. The Critical Path methodology identifies the paths of tasks most likely to impact the project completion date. Total slack: The total slack of an activity is the time this activity can be delayed without impact on the finish date of the project. Free slack: The free slack of an activity is the time this activity can be delayed without impact on the following activity. It’s automatically calculated into your project when you schedule tasks, and you can use it as buffer time if needed when your schedule is at risk of being delayed.

Slack, also called float, is the amount of time a task can slip before it bumps into another task.

What is free slack