What is a PERT Chart? Program Evaluation and Review Technique Guide

An integral part of project management is establishing an accurate project timeline before any work begins. Otherwise, missed deadlines can quickly snowball and derail the entire project. Fortunately, PERT charts are an easy solution for project managers looking for a more efficient way to schedule tasks.

Short for program (or project) evaluation and review technique, PERT charts or diagrams break down a project timeline into easily understandable milestones and activities. Specifically, they are used for particularly large and complex projects which involve many overlapping variables.

The visualized timeline acts as a starting point for determining every step necessary for a project to be completed on schedule. The diagram also coordinates between different tasks in order to optimize workflow into a more efficient sequence.

Originally made for the United States Navy in the late 1950s, most PERT charts follow the same pattern, like this template:

Wondering how to interpret the timeline shown above? Here is a brief explanation for how to create and best utilize PERT charts in your project management.

PERT: Defined

As mentioned above, the acronym PERT stands for: Program evaluation and review technique Or Project evaluation and review technique

Whatever terminology is preferred, the result is the same: a visualized timeline of a work project from start to finish. The only real difference between “program” and “project” PERT diagrams are scope, as a “program” may cover the schedule of multiple projects.

PERT Chart Terms

PERT diagrams can display a lot of information. In order to understand what’s possible with PERT charts, you first need to know the terminology:

• Node: A circular or rectangular shape which contains all information about a task event on the diagram
• Task Title: A name which identifies the task to be performed
• Task Duration: The amount of time a task is expected to take
• Start/End Date: When a task should start or be completed, along with early and late start/end alternatives
• Line or Vector: A literal line which connects related task nodes
• Dependency: What prerequisite tasks, if any, are necessary before a new task can be started
• Responsible Individual(s) or Team: Whoever is responsible for ensuring a task is completed
• Milestones: Specific deadlines used to denote progress or indicate a change to the project schedule
• Critical Path: The task sequence with the longest duration
• Lane: A way to categorize tasks into zones

All of this information is used to provide important context to the project timeline. All of these elements keep tasks moving forward and all relevant parties informed. The exact terms used may vary by industry, though the general ideas are the same.

Scheduling Projects with PERT Charts

PERT diagrams very closely resemble flow charts, though there are some distinct differences. For example, a detailed PERT chart may look like the following:

The lanes are designed to keep task nodes aligned based on when they need to be completed. How many lanes a chart has will vary from project to project. And color-coding can add to the readability of the diagram by marking each task in a specific color based on the responsible individual, team, or department.

Of course, other PERT charts need not be so detailed. Some may include task details over the vectors rather than the nodes. In these instances, it’s not uncommon for there to be a key in which tasks are assigned numbers in order to reduce text on the PERT chart. Others highly resemble flow charts, with almost no unnecessary details included within the diagram.

In this network diagram, task dependencies are defined by an exterior blue circle around the main node.

The Benefits of PERT Charts

The use of PERT charts provides many benefits to project managers who need a way to keep tasks moving on time. But there’s a lot more to these diagrams than just visualizing a project timeline.

The ability to track milestones and establish the critical path are two of the most crucial elements of PERT charts. First, milestones indicate which tasks are the most important for the overall project. Next, the critical path indicates the most efficient way to complete work. In fact, PERT charts are a variation of the Critical Path Method (CPM) of project management, a method which focuses on algorithm-based analysis of resources to calculate the ideal project timeline. These two methodologies are often used in conjunction with one another for maximum results.

PERT diagrams organize all your projects from start to finish. Beginning with the planning period, the chart will display a visual representation of everything a job needs to get done and when it needs to be finished.

How do PERT charts differ from GANTT and RACI charts?

There are many different methodologies when it comes to project management. Along with PERT charts, GANTT and RACI charts are extremely popular methods of organizing and planning out project tasks. Which style is right for you will depend on what qualities you need.

The greatest difference between PERT and GANTT charts is flexibility: PERT diagrams can be ordered in multiple ways while GANTT charts must be built out like bar graphs, with set X- and Y-axis. Every task must be placed within proper coordinates based on the start date. There is more freedom with PERT charts since tasks can be moved around based on dependencies rather than dates.

Similarly, PERT and RACI charts have some superficial similarities by organizing projects into estimated timelines based on tasks and milestones. However, as described above, the PERT chart is more focused on the schedule while a RACI matrix would simply detail the responsible parties assigned to each task.

The Importance of PERT Chart Software

Project management software can automatically generate PERT charts based on pre-existing or custom templates. Additionally, with software tools project timelines can be easily modified by anyone involved with the project. This can be done to reflect changes to major milestones or to establish a better Critical Path.

Cloud-based project management systems allow team members to review changes and record updates to the project tasks. Meet a milestone? Reassign a task? All of these updates can be viewed online. This increased visibility allows for clearer communication between everyone involved.

Finally, charts can be customized when generated by software. It’s intuitive to add additional lanes, categorize tasks, or simply color code different teams and departments.