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 the determination of the budget and time required for the achievement of a project’s goals.

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 the designing of the project’s network.


The difference between PERT and CPM is that PERT stands for Program Evaluation and Review Technique, and CPM stands for Critical Path Method. PERT manages unpredictable activities, whereas CPM manages predictable activities. PERT is related to the events, but CPM is related to the activities.


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 ModelProbabilistic model characterized by uncertainty in the duration of project completion.Deterministic model 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 reasonable forms.

What is PERT?

Project Management and Review Technique (PERT) is a statistical technique that is adopted for the determination of time that 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 in a manner 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 the planning, coordinating, scheduling, and controlling a project’s activity in a quest to manage both time and cost of a project.

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

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

Critical Path Method

Main Differences Between PERT and CPM

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


While the PERT technique is event-oriented, the CPM is an activity-oriented technique towards the determination of 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, most likely time, and the pessimistic time.

On the other hand, the CPM technique is a deterministic model. The technique’s deterministic tools offer an estimate that relates to 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 estimate.

The Technique’s Focus

The PERT technique lays focus on the time the project will reach its completion. 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 lays focus 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 cost of the project alongside the time of completion is essential.

Through this, project planners can adequately make decisions on 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 time of completion 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 for the estimation of 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 appropriated for the projects whose time estimations are under reasonable and flexible forms.

Difference Between PERT and CPM


  1. https://ascelibrary.org/doi/abs/10.1061/(ASCE)0733-9364(2000)126:3(219)
  2. https://books.google.co.in/books?hl=en&lr=&id=ODApoTanj4IC&oi=fnd&pg=PA1&dq=PERT+and+CPM&ots=y5xKkVNA5a&sig=ey7-Vc_m_riudGbO5nwm96vWDxw&redir_esc=y#v=onepage&q=PERT%20and%20CPM&f=false
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