Difference Between PERT and CPM

Excellent project management skills play a pivotal role in the success of a business enterprise. These skills are crucial in determining the budget and time required to achieve a project’s goals.


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PERT and CPM are the two standard statistical techniques adopted to ensure time consciousness and cost-effectiveness in the completion of projects.

However, the two techniques are different even though both lead to designing the project’s network.

Key Takeaways

  1. PERT (Program Evaluation and Review Technique) is a project management tool emphasizing time and uncertainty, while CPM (Critical Path Method) focuses on task duration and precedence relationships.
  2. PERT uses probabilistic time estimates to analyze and control project schedules, while CPM relies on deterministic time estimates for the same purpose.
  3. PERT is more suitable for complex, uncertain projects with high interdependency, while CPM is better for well-defined projects with clear task sequences.


PERT is an acronym that stands for project management and review technique, and it is a statistical tool that’s used to judge the timeframe in which a project can be completed. CPM means critical path method and it’s a technique used during the planning of a project to manage cost and time.


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In PERT, the prime focus is to plan and manage time, whereas in CPM, the prime focus is to control cost and time.

Comparison Table

Parameter of ComparisonPERT Technique CPM Technique
OrientationEvent-oriented technique.Activity-oriented technique.
Type of ModelThe probabilistic model is characterized by uncertainty in the duration of project completion.A deterministic model is characterized by certainty in the duration of project completion.
The Technique’s FocusFocus on the time of completion of a project.Focus on the time-cost trade-off in a project.
The Crashing ConceptThe crashing concept is not applicable.The crashing concept is applicable.
AppropriatenessSuitable for high precision time estimation of projects that are unpredictable and whose activities are non-repetitive.Suitable for projects that are predictable and whose activities are repetitive. Time estimation for such projects is made under appropriate forms.

What is PERT?

Project Management and Review Technique (PERT) is a statistical technique adopted to determine the time a project should take to complete.

Notably, the PERT technique is resourceful when dealing with unpredictable activities in a project since it accounts for uncertainties that might occur.

This is achieved by controlling the uncertainties so that the time allocated for the project is not affected.

Project Management and Review Technique

What is CPM?

Critical Path Method (CPM) refers to a management technique employed in planning, coordinating, scheduling, and controlling a project’s activity to manage both time and cost.

CPM technique is highly recommended for projects whose activities are predictable, for example, house construction.

The technique assesses the earliest and latest possible time to start each project activity.

Critical Path Method

Main Differences Between PERT and CPM

The two methods remain very different despite PERT and CPM techniques being used in designing a project’s activities network. The following are critical differences between PERT and CPM techniques.


While the PERT technique is event-oriented, the CPM is activity-oriented for determining the cost and time to be taken from the start till the end of a project.

That is, the PERT network chart is constructed based on the events of the project at hand. On the other hand, a CPM chart network is developed based on jobs that make up the whole project.

Type of Model

The PERT technique is a probabilistic model characterized by uncertainty in the project duration. The tools in the PERT technique give several estimates for the calculation of the time of project completion.

The expected time for the end of the project is calculated from the optimistic time, the most likely time, and the pessimistic time.

On the other hand, the CPM technique is a deterministic model. The technique’s deterministic tools estimate the cost and amount of money available for a project’s completion.

Unlike the PERT technique, which provides three estimates, the CPM offers only one.

The Technique’s Focus

The PERT technique focuses on the time the project will complete. Three estimates determine the time of completion of a project.

These include the optimistic or most promising time (to), the pessimistic or unfavorable time (tp), and the most likely or promising time ™.

Unlike the PERT technique, the CPM technique focuses on the trade-off between the time and cost for the completion of a project.

To the project managers adopting the CPM technique, optimization of the project’s cost alongside the completion time is essential.

Through this, project planners can adequately decide which aspects of a project are trade-offs necessary.

The Crashing Concept

The crashing concept refers to the compression theory of shortening a project’s completion time alongside the least additional cost.

Notably, the crashing concept does not apply to the PERT technique since there lacks certainty in time, making it hard to alter the activity duration.

On the other side, the crashing concept applies to the CPM technique.

With the certainty of the completion time, project planners and managers can alter the duration of a project alongside the least additional time.


The PERT technique is most suitable for research and development projects. These include projects where resources are always available as required.

A project with unpredictable activities is well managed using the PERT technique.

Additionally, the PERT technique is best used to estimate high precision time of duration of the project whose activities are non-repetitive.

On the other hand, the CPM technique is best suited for non-research-based projects such as civil construction.

All projects whose activities are predictable and repetitive are well managed with the help of the CPM technique.

Additionally, the CPM technique is appropriate for projects with time estimations under proper and flexible forms.

Difference Between PERT and CPM
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