CPM Chart: The Ultimate Guide to Using CPM Charts

There are certain tasks or projects that go beyond mere planning. It is not easy, therefore, to determine how long they will take or where to begin. Without a critical plan, such tasks or projects lack credibility. On the other hand, stakeholders and project managers need to manage expectations and deadlines efficiently.  Unless there is a clearly outlined path, it is impossible to envision the outline of a project. This is where the critical path method (CPM) comes in. CPM identifies and schedules critical task sequences and determines how much time a project will need up until its completion.

What is a CPM chart?

CPM, which stands for Critical Path Method, is an algorithm of resource-utilization that schedules a set of project activities. CPM is used to construct a project model that includes:

  • A task list required for project completion
  • Tasks dependencies
  • Estimated duration taken by each activity to be completed

A critical path can be determined by identifying the dependent activities' longest stretch and measuring them from beginning to the end.

Having identified the longest activities, you can discern easily which activities have total float or those which can be delayed without lengthening the project.

This enables you to calculate time durations, discern the individual tasks' importance, and make a comparison of actual and planned progress of your project through completion.

To get a better understanding of the CPM chart definition, the Project Management Institute defines a CPM chart as a sequence of activities that are scheduled to determine the total duration of a project. For a project to be regarded as a success, these scheduled activities must be performed in a specific order.

You cannot fully grasp the concept of critical path unless you first understand the various terms used.

  • Earliest Start Time (ES): This is the earliest time when a task can be started in the project. First you need to know whether there are preceding tasks or constraints which may impact the start of a task.
  • Latest Start Time (LS): This refers to the very last minute when a task can be started without which your project schedule is thrown into disarray.
  • Earliest Finish Time (LF): Based on the duration and the earliest start time, it is the earliest time an activity can be completed.
  • Latest Finish Time (LF): This is the latest time an activity can be completed based on the latest start time.
  • Float: This is the length of time during which a project's delay doesn't impact and threaten the project's deadline.
  • Crash Duration: This is the shortest time duration within which a task can be scheduled.
  • Critical Path Drag: This refers to a situation where, due to a constraint, the project's time is added.

How to create a CPM chart

Without a CPM chart, project planning can prove to be a little tricky, and you may lose track of tasks and their priorities.  If you are wondering how to make a CPM chart, there are a few steps that must be followed to the letter.

  • Make a list of each specific task
  • Establish activity sequence
  • Make a drawing of the network diagram
  • Make an estimation of task completion time
  • Having made a list of each specific task, you can now identify the critical path
  • Update the CPM diagram to show progress

CPM chart software

During the early stages of CPM development, a critical path was identified by hand. A network diagram with nodes was drawn to represent the projects' stages while the nodes were connected using arcs.

This was time-consuming and quite difficult, especially when there are constantly changing aspects during the beginning of a project. But that has now changed as there are software programs available to assist in project management with a click of a button.

Effective CPM chart software schedules critical task sequences and events in order to determine a project's duration and completion.

CPM chart software allows you to calculate a project's time durations, determine individual task importance, and make a comparison between actual and planned progress in your project until it is complete.

CPM chart software allows you the following:

  • Easy to use formulas
  • Automatic updates on dates and task durations
  • Real-time addition of formulas as well as custom data fields


Having read and understood all about the CPM chart, it is time to give it a trial and experience a whole new world of efficiency in project management.

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