Critical Path Method Calculations

Instructions: Use this SkillGuide as a reference to the calculations used in the Critical Path Method. A one-to-one dependency means a task has one dependent task that immediately follows it. A one-to-many dependency means a task has two or more dependent tasks that immediately follow it. A many-to-one dependency means there are two or more tasks on which a single task depends. The dependency type is determined by the sequence in which tasks will be performed in a project.

Note: The example used in this job aid uses the beginning of the business day as a reference point.

	One-to-one dependency between tasks
	Forward Pass: Early Start date + Duration = Early Finish date Move the Early Finish date to the Early Start date of the next activity. Backward Pass: Late Finish date – Duration = Late Start date Move the Late Start date to the Late Finish date of the previous activity.
	One-to-many dependency between tasks
	Forward Pass: Early Start date + Duration = Early Finish date Move the Early Finish date to the Early Start date of all dependent activities. Backward Pass: Late Finish date – Duration = Late Start date Move the smaller Late Start date to the Late Finish date of the previous activities.
	Many-to-one dependency between tasks
	Forward Pass: Early Start date + Duration = Early Finish date Move the larger Early Finish date to the Early Start date of all dependent activities. Backward Pass: Late Finish date – Duration = Late Start date Move the Late Start date to the Late Finish date of the previous activities.