This article will help you to learn about the difference between PERT and CPM.

Difference between PERT and CPM


1. A probabilistic model with uncertainty A deterministic model with well-known activity in activity duration. Expected time is (single) times based upon past experience, calculated from to, tm and tp.

2. An event-oriented approach.

3. PERT terminology uses words like network diagram, events, and slack.


4. The use of dummy activities is required for representing the proper sequencing.

5. PERT basically does not demarcate between critical and non-critical activities.

6. PERT finds applications in projects where resources (men, materials and specially money) are always made available as and when required.

7. Especially suitable in defence projects and R & D where activity times cannot be reliably predicted.


1. A deterministic model with well-known activity (single) times based upon past experience. It assumes that, the expected time is actually the time taken.


2. An activity-oriented system.

3. CPM terminology employs words like arrow diagram, nodes and float.

4. The use of dummy activities is not necessary. The arrow diagram thus becomes slightly simpler.


5. CPM marks critical activities.

6. CPM is employed to those projects where minimum overall costs is of primary importance. There is better utilization of resources.

7. Suitable for problems in Industrial setting, plant maintenance, civil construction projects, etc.