If you’ve ever struggled with mapping project tasks or keeping track of dependencies, we have the perfect solution for you.
A PERT chart, also known as a PERT diagram, is a tool used to schedule, organize, and map out tasks within a project.
PERT stands for program evaluation and review technique. It provides a visual representation of a project's timeline and breaks down individual tasks. These charts are similar to Gantt charts, but structured differently.
This diagram consists of a few steps to get you from a project start date to end date. In this article, we’ll cover the five steps, show you an example, and explain how to effectively use a PERT chart to your advantage.
A PERT chart works by visually representing a project’s tasks and the dependencies connected to each one. You might use one to create an initial schedule and estimated timeline to share with project stakeholders before the project actually begins.
Creating a project roadmap such as a PERT chart can help you accomplish several project planning activities, including:
Getting schedule and timeline signoff from leadership
Communicating project objectives to stakeholders
Visually mapping out a complex project
Estimating the time needed to complete individual tasks
In order to make the most of your PERT chart, you should first understand the steps needed to complete one and how to visually map out your diagram.
To create a PERT chart, follow the five steps of the process lifecycle, which includes everything from identifying tasks to managing project completion.
The first step in creating a successful PERT chart involves identifying and collecting necessary project information and tasks. You can begin the project planning phase similar to how you’d typically start the initial project management phase. This can include:
Early planning ensures that you’re prepared to defined dependencies and connect tasks during the next phases.Free meeting agenda template
A task dependency is a task or milestone that relies on another task to be completed before the task at hand can be started. This is sometimes referred to as a logical relationship and is often used in a work breakdown structure.
Creating dependencies can help you properly track work, ensure tasks are completed, and establish clear communication. For complex projects, plan timelines and project duration properly ahead of time.
In a PERT diagram, dependencies are visualized by connecting and numbering tasks. While not as comprehensive as other methods like a work breakdown structure, it helps to show a high-level visualization of tasks and the work needed to complete them.Read: 12 tips to effective communication in the workplace
Once task dependencies have been created, you can work on creating your PERT chart by connecting project tasks to one another. These connections consist of arrows, which represent tasks, and nodes, which represent events or milestones.
For example, place parent events within your nodes (represented as numbered circles or squares) and draw task arrows to represent the dependencies needed to complete your events.
This layout provides a simple project structure that, while not overly specific, is easily comprehensible for project stakeholders.
Now it’s time to estimate your overall project time frame using the critical path method (CPM) and the PERT formula. The critical path is the longest sequence of tasks that must be completed to successfully finish a project.
The objective is to find the longest path that will take the most time to complete in order to estimate the shortest overall project duration. Time estimates can be calculated based on the following:
Optimistic time: The minimum amount of time needed to accomplish a task.
Pessimistic time: The maximum amount of time needed to accomplish a task.
Most likely time: The best estimate of how long it will likely take to accomplish a task.
You can use the PERT formula to calculate the expected duration of a task and completion time using: (O + (4 × M) + P) ÷ 6. This can be measured by minutes, hours, days, or even weeks.
For example, if the optimistic time is 30 minutes, the pessimistic time is 60 minutes, and the most likely time is 45 minutes, the PERT formula would be: (30min + (4 × 45min) + 60min) ÷ 6 = 45 minutes.
Once you’ve calculated the expected time per task, you can then add each of the estimates of your critical path together to get an average project timeline.
The final step in creating a PERT chart is to manage task progress to project completion. This can be done by closing dependencies and mitigating issues along the way until all tasks are completed.
Remember that a PERT diagram should be updated throughout the project as changes occur. This could be paired with a change control process, which helps map and communicate project changes.
Once all tasks within the project have been completed, you can archive materials in a shared space to be referred to later on if needed.Read: Why a clear communication plan is more important than you think
Now that you understand the five steps of a PERT chart, it’s time to create one of your own. Since all diagrams differ depending on the complexity and time frame of a given project, yours might look slightly different.
To start your chart, begin by:
Drawing your numbered nodes: Remember, these are the parent tasks of your project which, when completed, will make up the project at hand. Your diagram may have any number of tasks, but 10 is a good number to start with.
Connect your nodes to tasks: Draw arrows to represent task dependencies. These tasks are what need to be done for the events to be completed. Your diagram should have a clear beginning and end, though the middle may look more complex.
Here’s an example of what your PERT chart should look like:
Here is a breakdown of common terminology you may include in your PERT chart and the definition for each:
Nodes: Nodes represent project events. These events are the large components that make up your project. For example, when launching a website design, a node might represent a new logo design.
Tasks: Your tasks are what need to be completed in order for your nodes to be implemented. For example, a task might represent designing three logo mockups.
Dependencies: A dependency is when a task is connected to another task. These tasks rely on one another and one cannot be completed without the other.
Dependencies without resources: A dependency without resources is one that, while connected to another, doesn’t have tangible tasks that need to be completed. For example, while a product launch and landing page might be correlated, no one task is connected to each.
PERT charts can be created using a variety of tools, including project management software. Tools can help you properly plan, visualize, and set up task dependencies and reminders in order to track project progress and easily spot bottlenecks.Read: 3 ways to visualize a project plan: Timelines, calendars, and boards
Project managers use PERT charts to evaluate and complete a given project. But with so many other methods to choose from, how does a PERT diagram compare?
For starters, a PERT chart is a good method when you’re looking to evaluate the timeline, resources needed, and a project’s critical path. Let’s look at each of these a little closer.
To determine the critical path: One of the key features of a PERT chart that sets it apart from other methods is its ability to determine a project’s critical path. This is important when visualizing the overall timeline of a project.
To evaluate resources: With the unique features a PERT chart offers, you can easily display which tasks require resources and which don’t. This saves both you and project stakeholders time by having that information upfront and accessible.
To estimate time: Since a PERT chart evaluates both individual task duration and overall project duration, it’s a great tool when you need to understand the expected timeline during the initial project planning phase.
Overall, creating a PERT chart is a good option for a simple project plan that can easily be shared with team members. Use this chart to quickly share resources and timelines.
PERT charts and Gantt charts are often confused, though they have a few key differences. Not only do they differ in their visual appearance, but they also provide different features depending on what your team needs.
Here are a few key features to note when deciding on which one is right for you:
PERT charts are flowcharts while Gantt charts are bar graphs: One of the biggest differences is their visual layout. While Gantt charts take on a traditional bar chart approach, PERT charts are less structured in appearance and take on different layouts depending on the project.
Gantt charts offer organization while PERT charts offer customization: Gantt charts are more structurally organized. On the other hand, PERT charts allow simple layout customization which is better for high-level project needs.
PERT charts can be used before the project begins: Since PERT charts offer a simple project plan and timeline layout, they’re often used as visual guides during the project kickoff. Project managers then use another method, like a work breakdown structure or Gantt chart, to specifically map project tasks and dependencies.
In general, Gantt charts are more popular for mapping out project tasks throughout the project lifecycle while PERT charts are popular for time mapping in the initial project stages. They can be used separately or together to create a comprehensive plan.
By implementing a PERT diagram of your own, you can be sure your next project is planned accurately and correctly. With a simple layout and timeline estimates, your team will have clear direction on project tasks and be prepared for whatever comes their way.Try timeline with Asana for free