PERT in Project Management

Man on phone behind desktop

The more tools a project manager has, the more they can do. But it’s also important to know which tools are right for each job and how to use them effectively. One such tool is a program evaluation review technique (PERT) chart. PERT charts can help determine timelines, establish priorities, and identify potential roadblocks. This article serves as a practical guide for understanding and constructing PERT charts in project management.

Take a product tour

What is PERT?

A PERT chart provides a map of a project as a network diagram. A node (such as a circle or rectangle) in the diagram represents each task associated with the project. Nodes connect with arrows indicating the order of tasks and task dependencies.

A completed PERT chart allows the entire project’s visualization, including time estimates for each task and which tasks to complete first. Teams can see potential bottlenecks and identify a critical path (the dependent task chain estimated to take the longest total time).

PERT charts: history and goals.

The United States Navy developed the PERT chart in the late 1950s to help organize the Polaris nuclear submarine project. Now, the military, business world, and beyond use PERT charts to simplify the planning of large and complex projects.

Typically, teams create a PERT chart before a project begins to gauge its full scope, identify potential issues, and map out an appropriate timeline. This chart contrasts with another project planning tool, the GANTT chart, which organizations primarily use to monitor project progress. PERT charts also provide insights that GANTT charts often do not, including creating a clearer depiction of task hierarchies and interdependencies and estimating the entire timeline and variability.

When utilizing a PERT chart, there are four types of timelines:

Expected time = (O + 4M + P)/6

Additionally, you can calculate the variance as (P - O)/6 to estimate how much the actual time may deviate from the expected time.

Benefits of PERT charts in project management.

PERT charts enable new insights regarding project trajectories and timelines, identifying possible bottlenecks, constraints, and new opportunities for unseen efficiencies.

Advantages of PERT charts in project management include the ability to:

How to create a PERT chart for your project.

Here are the steps for creating a PERT chart so that you can understand the process and get started:

1. Break project milestones and goals into constituent tasks.

First, identify all major milestones or deliverables for the project. Then, break each of these down further into a list of tasks to complete to achieve the milestone. You may wish to consult the team or department leaders to make sure you don’t overlook anything.

2. Determine which tasks are prerequisites for others.

Building off the previous step, you next need to identify task dependencies. Some tasks can be completed in isolation during the project, while others are on hold until the team finishes a prerequisite task. Again, in collaboration with team leaders, identify these interdependencies.

3. Estimate the time frame associated with each task.

Next, you need to add time estimates for each task. While you can ask those whose job it is to complete the tasks for their best estimates, people aren’t always the best judge of time frames and can be overly optimistic. Consider looking at past projects with similar tasks to get an idea of how much time each task might take. Ideally, you should note a range of possible times for each task so that you can adjust the overall timeline later on.

4. Translate your tasks and milestones into nodes.

Begin creating the chart by arranging each task and milestone on a large diagram. Nodes should represent these tasks. Note that as you begin the next step, you may need to move the nodes around, so sketching things out on a whiteboard or in a computer program will make this easier.

5. Draw vectors between tasks.

Using your notes on task prerequisites and interdependencies, draw arrows between your nodes to indicate which tasks form dependent chains. Keep in mind that you can have parallel chains if some tasks do not affect others. You may also want to include time estimates on the nodes or the arrows connecting the nodes so that you can later estimate the entire project time.

6. Analyze and optimize.

Once you draft your PERT diagram, look for ways to rearrange or break up tasks to optimize for time and minimize potential bottlenecks or problems. Refine your diagram until it is as clear and comprehensive as possible.

Chart a path forward.

If you’re a project manager, you juggle many responsibilities as you plan and organize projects of varying complexity and scale. Having the right tools and knowing how and when to use them is vital. We hope the information in this article proves helpful as you expand your project management toolbox to include PERT charts.