Enter the optimistic, most likely, and pessimistic times into the PERT calculator to determine the expected time for your project task.

PERT Calculation Formula

The following formula is used to calculate the expected time (E) in PERT analysis:

E = (O + 4M + P) / 6

Variables:

  • O is the Optimistic Time (days)
  • M is the Most Likely Time (days)
  • P is the Pessimistic Time (days)
  • E is the Expected Time (days)

To calculate the expected time, use the formula above by plugging in the values for optimistic, most likely, and pessimistic times.

What is PERT?

PERT, or Program Evaluation Review Technique, is a project management tool used to schedule, organize, and coordinate tasks within a project. It focuses on the time required to complete each task and helps project managers estimate the total time needed to complete a project.

How to Calculate Expected Time in PERT?

The following steps outline how to calculate the expected time using the PERT formula:

  1. Determine the Optimistic Time (O): The shortest time in which you can complete the task.
  2. Determine the Most Likely Time (M): The best estimate of the time required to complete the task, assuming everything goes as usual.
  3. Determine the Pessimistic Time (P): The longest time it might take to complete the task, assuming everything goes wrong.
  4. Use the formula: Expected Time (E) = (O + 4M + P) / 6
  5. Calculate the expected time by inserting the values into the formula.

Example Problem:

Use the following variables as an example problem to test your knowledge:

Optimistic Time (O) = 3 days

Most Likely Time (M) = 5 days

Pessimistic Time (P) = 9 days

Using the formula: E = (O + 4M + P) / 6 = (3 + 4*5 + 9) / 6 = 5.33 days

FAQ

1. What is the purpose of PERT?

PERT is used for planning and controlling large and complex projects, helping to analyze the time required to complete each task and the entire project.

2. How does PERT help in project management?

PERT helps project managers identify the minimum time needed to complete a project, understand task dependencies, and evaluate potential delays.

3. What is the difference between PERT and CPM?

PERT focuses on time estimation and is probabilistic, while CPM (Critical Path Method) focuses on task dependencies and is deterministic.

4. Can PERT be used for all projects?

PERT is most useful for projects with a high degree of uncertainty in task completion times, such as research and development projects.

5. How often should I update my PERT chart?

It’s important to update your PERT chart regularly, especially after completing key tasks or when project conditions change significantly.