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**Table of Content**

With the help of this PERT calculator, you can find out the expected completion time of a project, the standard deviation, and the chance of completing the project in the desired time frame.

This handy tool is solely designed to help the contractors find the expected time duration for the completion of a project so that they can provide the correct estimation about the completion of a project.

PERT (Program Evaluation and Review Technique) is a way of calculating the time required for the completion of a project and it determines a Critical Path Method variation (CPM).

It is helpful in scheduling all the tasks and also helps in defining the right project completion time for the client. This calculation includes the following estimations:

Estimation of all the conditions without any risks.

It includes both favorable and unfavorable conditions.

This estimation includes all the negative risks.

Have a look at the following PERT method formula to calculate this parameter manually:

\(T_{E}\) **= (O + 4M + P) / 6**

**SD = (P – O) / 6**

Where

- \(T_{E}\) represents the Pert Expected Time Duration
- O is the optimistic estimation
- P shows the pessimistic estimation
- M is the most likely estimate
- SD is the representative of the
**standard deviation**

If it seems difficult to calculate the PERT manually, then for PERT estimating get the help of a pert calculator. It will allow you to perform precise calculations effortlessly.

Let’s suppose there is a contractor who is expected to complete a project in 2 years and has the following estimations:

- Optimistic Estimate (O) = 14 months
- Most Likely Estimate (M) = 16 months
- Pessimistic Estimate (P) = 22 months

Now how to calculate PERT?

Given that:

O = 12 months

M = 18 months

P = 24 months

Put these values in the PERT estimation formula:

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

T_E = (14 + (4 x M) + P) / 6

T_E = (14 + (4 x 16) + 22) / 6

T_E = (14 + (64) + 22) / 6

T_E = (14 + 64 + 22) / 6

T_E = 100 / 6

T_E = 16.67

Now

SD = (P – O) / 6

SD = (22-14) / 6 = 8 /6

SD = 1.33

According to this, the contractor will be able to complete the work in 16.67 months with a standard deviation of 1.33 months. Check out more pert formula examples to make the concept clear in your mind so that you can perform the manual calculation correctly.

Get the assistance of our easy-to-use PERT formula calculator to estimate PERT in no time. Let’s see how it works!

**Inputs:**

- Add the values of “Optimistic Estimate”, and “Most Likely Estimate”
- Likewise, enter the “Pessimistic Estimate”, and “Desired Completion Time” in the specified fields
- Set the required “PERT” and “Standard Deviation” units
- Tap on the “Calculate” button

**Output:**

- PERT
- Standard Deviation
- Probability of Completion

- Requires to identify all the defined activities
- Understanding the way or sequence in which the activities have to be performed
- Creation of network diagram
- Know the critical path
- Estimate of time for the completion of each task
- Changing and updating of the PERT Chart

PERT is very useful in making the right plan for managing all the tasks of a project efficiently.

Let’s take a look at the below-mentioned benefits of PERT calculation:

- Helps in evaluating the time and resources
- Informs about the requirements of all activities
- Allows to anticipate the actions in a project
- Helps to account for the uncertainty

The digit 4 in the PERT estimate formula shows that we are estimating the PERT by considering the factor of 4 and getting the average of the weighted most likely time, including the best and worst scenarios.

This is the weighted average in which M is four different times of sum, now you have six total terms and therefore it is divided by 6.

From the source of acqnotes.com: PERT Analysis

From the source of Wikipedia: PERT, Terminology