Skip to main content Skip to footer
Project management

Build better project plans with PERT analysis 9 min read
Get Started

Project planning can seem simple. That is, until you find yourself missing deadlines.

You may think you’re realistic in setting due dates. But, if your team is struggling to keep up, your project planning technique isn’t working.

But it’s not your fault!

For some projects, if one thing falls through the cracks, the whole project can quickly go off the rails.

Even if you account for dependencies in a Gantt chart, that doesn’t guarantee that project tasks are getting done on time to keep things moving forward.

If you’re struggling to plan projects accurately, PERT analysis may be able to help.

While it may be time-consuming, this old-school planning technique is one way to change the way you look at deadlines and create more realistic project schedules.

In this article, we’ll explain what the PERT method is, when you should and shouldn’t use it, and better alternatives for project planning.

What is PERT analysis?

Many companies think they need to choose one project planning technique and stick to it.

But, most experienced project managers know that having different planning tools up their sleeve can come in handy on a complex project.

For projects with more dependencies than you’re used to, the Program Evaluation and Review Technique (PERT) can help make your project plans more reliable.

Even though the PERT method has been around since 1957, it’s a solid technique for planning large projects in some cases, like when your project has more moving parts than you’re used to.

The PERT method looks at each project step and how they relate to one another.

A PERT chart shows which tasks each step of the project is dependent on. That way, it’s clear that if activity A isn’t done, no one can start activity B.

Demonstration of a PERT diagram showing project task dependencies and a number of how long each task will take

(Image Source)

When all the tasks and their dependencies are displayed in a PERT diagram, you can use a dedicated formula to decide how much time each step needs.

The PERT formula is: (O + 4M + P)/6. In this formula, the P = pessimistic case, O = optimistic case, and M = most likely case.

First, you approximate how many days you expect the task to take, which can represent the most likely case.

Then, you estimate how long the same task will take if everything goes according to plan (the optimistic case) and if everything does not go according to plan (the pessimistic case).

Plugging these 3 estimates into the formula can help you calculate an average task duration for your project schedule.

While creating a full PERT chart can be time-consuming, it also helps give more realistic time estimates for long-term projects.

These nuanced deadlines can also help you set better project schedule durations by looking intently at how much time each task may take, and how a missed deadline will impact the rest of the project.

When 67% of project managers say projects have gotten more complex over the past decade, using a variety of project planning tools simply makes sense.

Creating your project schedule with PERT analysis is one way to make managing project expectations easier down the line. However, in many instances, PERT analysis isn’t the best use of your time during the project planning phase.

Get started with

What’s the difference between PERT analysis and critical path analysis (CPA)?

If PERT analysis sounds suspiciously like critical path analysis to you, you’re on the right track.

These techniques are similar, but there is one distinct difference that sets the PERT method apart.

Critical path analysis (CPA) lays out all the dependent tasks and events that could get in the way of project completion. After you plot out all the potential paths from your project’s start to completion, the path that takes the longest is the critical path.

By finding the “critical path,” you can see how long your entire project could take. But, to create an accurate critical path, you have to know how long each task will take — the task duration.

If your company is one of the 39% of organizations that don’t regularly set project baselines, your estimates for how long something takes may be way off.

Diagram showing that significant numbers of organizations only baseline project schedules half the time or less.

(Image Source)

In a traditional CPA model, you just pick one duration for each task or activity.

With a PERT analysis, you use the PERT formula to find 3 potential durations, instead of one.

When you plug the 3 estimated durations into the formula, you can predict approximately how long each task will take.

While it can take a long time to plot out each path, PERT analysis can help you create more accurate project schedules than CPA, when there’s a lot of uncertainty in your project.

What are the benefits of PERT analysis?

Better baselining makes it easier to budget effectively, set better deadlines, and reserve the right resources for your project. The PERT formula can provide clarity on how long your total project may last by taking a close look at the potential durations of each task.

Each task on a PERT diagram has an estimated value that helps a project manager better predict how long each step needs during project planning.

With the PERT formula, the most likely case is weighted 4x as much as the other values. The most likely case accounts for everyday problems and opportunities. The weighted average calculated by the PERT formula is what gives this technique its staying power.

Every project manager knows that a thorough product plan leads to a project that’s more likely to be delivered on budget, on time, and within its original scope. While the PERT technique takes a lot of time during the planning phase, it can help you save time down the line.

Diagram showing that only 29% of organizations mostly or always complete projects on time

(Image Source)

When only 29% of organizations say projects are usually completed on time, it’s clear that many PMs could use some help estimating project duration.

When a critical project has a lot of what-ifs, PERT analysis can offer the clarity you need to succeed.

What are the drawbacks of PERT analysis?

In many ways, PERT analysis is an outdated way to manage modern project planning.

PERT does not offer the flexibility that other project scheduling techniques offer. For instance, since PERT charts are usually hand-drawn, they fall short of more flexible tools like Gantt charts, which can be quickly updated throughout a project.

You often don’t have enough information before a project for a PERT chart to be useful, either. While planning is a crucial part of project management, you may not have the detail needed to effectively create a practical PERT chart.

After all, the output is only as good as the estimates that you provide. If you’re just pulling numbers out of your hat, then PERT analysis becomes a colossal waste of time.

Yet, once a project is started, a PERT diagram usually falls to the wayside, since it’s so time-consuming to update as things change.

Bottom line: this old-school method takes a lot of time and effort to execute. Your resources and time are often better spent on creating adjustable schedules and resource allocation plans in your dashboard.

Better project planning with

While manual PERT analysis may be useful for complex projects, there are many better ways to create accurate project plans digitally.

No matter how big or complex your project is, can make it easier to manage from start to finish.

Flexibility is a major part of modern project planning, and offers a robust and customizable way to continuously update project forecasts and keep your project moving forward.

The project timeline template is a great place to start when you’re identifying your project tasks.

Once you’ve identified your tasks, you can manually use the PERT formula to find the most likely number of days each step will take.

The data from your PERT analysis can help you create a project schedule to start your project, while your Gantt chart and timeline templates can show the actual progress of your project. project timeline template dashboard with project tasks divided into phases.

In most cases, the PERT method isn’t the best use of your time. If you can accurately pinpoint task duration, there’s no need to do unnecessary manual calculations.

But, when there are some lingering questions about how long your project will take, pulling out the PERT formula can add extra clarity to your project plan.

Creating a project timeline with is a faster and easier solution to plan your project. Plus, having all your project planning documents on one dashboard makes it easy to alter and edit your project.

Create a powerful project plan today

PERT analysis can be a powerful tool to determine your initial scheduling estimates. When you have a complex project on your plate, having techniques like the PERT method up your sleeve can make project planning easier.

However, when it comes to managing your project, you need something more robust to turn those project plans into reality. That’s where comes in.

A powerful Work OS like can help you examine your plan and your actual timelines from one easy-to-use platform.

With 8+ ways to view your project dashboard, you can make visualizing your project and setting effective deadlines a breeze with

Effective projects need the right resources from start to finish. Get started with our project timeline template on today.

Get started

Get started