What is the Difference Between PERT and CPM

Difference Between PERT and CPM

Table of Content:

  1. What is CPM
  2. PERT vs CPM
  3. Advantages of PERT
  4. PERT Example
  5. CPM Advantages
  6. CPM Example
  7. FAQs

Project management can be defined as a structural way of planning, scheduling, executing, monitoring, and controlling various phases of a project. To achieve the end goal of a project on time, PERT and CPM are two project management techniques that every management should implement. These techniques help in displaying the progress and series of actions and events of a project.

Meaning of PERT

Program (Project) Evaluation and Review Technique (PERT) in an activity to understand the planning, arranging, scheduling, coordinating, and governing of a project. This program helps to understand the technique of a study taken to complete a project, identify the least and minimum time is taken to complete the whole project. PERT was developed in the 1950s, with the aim to the cost and time of a project.

In PERT, the project is segregated into events and activities. After discovering a proper sequence, the network is built. It is then the time for each task is calculated, and a path is regulated.

Meaning of CPM

Critical Path Method (CPM) developed in the 1950s is an algorithm needed for planning, arranging, scheduling, coordinating, and governing of a project. It is presumed that in this method the activity time is specified and fixed. It is used to calculate the quickest and latest start time for each task.

CPM helps to distinguish the critical and non-critical tasks, reduces the time and bypass the queue formation in the process. It is essential to identify critical activity because if any activity is hindered, it will clutter the whole process.

In this process, first, the list of all the activity is prepared, followed by the time required by each of these activities. Then the dependency connecting the activities is decided. Here, the series of the activity in a network is defined as ‘path’.


Full Form Full form of PERT- Program (Project) Evaluation and Review Technique Full Form of CPM-Critical Path Method
Meaning PERT is a technique, used to manage the uncertain task of a project. CPM is a statistical technique used to manage the activities of a project.
Method To control time To control cost and time
Progress Research and development project Construction project
Manage Unpredictable activities Predictable activities
Appropriate for Research & Development project Non-research project. Example-ship building, civil construction

Advantages of PERT

  • Planning for Large Project- It is used in scheduling large project by the project manager
  • Visibility of Critical Path- It is used to show the critical path in a clear way. The critical path those paths were activities cannot be paused under any conditions.
  • Analysis of Activity- This will provide the management with the progress report and the completion of the project including the budget.
  • Coordination Ability-This helps in improving the communication within different departments of the company.
  • The What-if Analysis– This analysis benefits the company to recognize the risk linked with any projects.

Disadvantages of PERT

  • Time Focused Method- PERT is a time-bound method, so finishing project or activities on time is of high importance. If it does not happen than a problem can arise
  • Subjective Analysis- Here, the project activities are recognized according to the available data. However, it is difficult in PEERT projects as it is applicable for the only new project are which is not repetitive in nature, therefore, the collection of information to be subjective in nature.
  • Prediction Inaccuracy- PERT does not have any past records for a framework of a project, so prediction comes into play. The project will be ruined if the prediction is not accurate.
  • Expensive- Too expensive in terms of time consumed, research, prediction, and resources utilized.

>PERT Example

PERT Example

Advantages of CPM

  • Provides an outline for long term coordination and planning of a project.
  • Recognizes critical activities
  • Easy to plan, schedule, and control project
  • It improves productivity
  • Manages the resource needed

Disadvantages of CPM

  • For beginners its difficult to understand
  • Software too expensive
  • Sometimes, to structure CPM is too time-consuming
  • It cannot control and form the schedule of a person involved in the project
  • Allocation of resources cannot be monitored properly

CPM Example

CPM Example

How to Make a PERT Chart?

To prepare a PERT Chart following steps needs to be followed.

  • Recognize particular projects and milestones.
  • Decide the precise sequence of the project.
  • Create a network diagram.
  • Determine the time needed for each project activities.
  • Manage the critical path.
  • Update the PERT chart as the project progresses.

CPM in Project Management

The Critical Path Method in project management is a step-by-step technique used in the planning process that explains the critical and non-critical activities of a project. CPM goals are to check time-bound issues and process that causes blockage in the project. The CPM is preferably applicable to projects that involve various activities that are associated in a complex method.

Once CPM is applied, it will help you keep your projects on track.

  • Help you recognize the action that needs to be performed on time so that the whole project is completed on time.
  • Indicates which responsibilities can be delayed and for how long without affecting the overall project plan.
  • Determine the least amount of time it will take to accomplish the project.
  • Tell you the newest and latest time each activity can start on in order to manage the schedule.

The term of each action is listed above each joint in the diagram. For an individual path, insert the duration of each node to ascertain the total duration. The critical path is the one that has the longest duration.

The above mentioned is the concept, that is elucidated in detail about ‘PERT vs CPM’ for the Commerce students. To know more, stay tuned to BYJU’S.

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Frequently Asked Questions

What is PERT and CPM?

Programs or Project Management and Review Technique (PERT) is apt for those projects where the time required to accomplish different activities are not known. CPM or Critical Path Method is appropriate for the projects which are reappearing (recurring) in nature.

What is a CPM used for?

CPM or Critical Path Method is used to assist the project manager in scheduling the activities. It presumes that activity time period is known with certainty.

When to use PERT and CPM?

PERT is stipulated according to events whilst CPM is ranged towards activities. A deterministic model is used in CPM. While PERT uses a probabilistic model.

How PERT is Calculated?

PERT is an estimating technique that uses a weighted average of 3 numbers to come up with a final estimate. The following PERT estimate is computed as (O + 4M + P)/6. This is known as “weighted average”.

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