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What is a CPM schedule & how to use it in project management

Get the details on building a specific timetable for your CPM-planned project

The

Critical Path Method (CPM)⁠

is a project planning technique created in the 1950s by engineers at DuPont. Project managers use CPM to identify the most important series of tasks in a big project. It's been a project management standard in lots of industries (especially the construction industry) because, without it, managing complex projects can feel like taking a calculus exam every single day.

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Managing a complex project without CPM.

The true power of the CPM method comes out when you apply a specific, detailed schedule to it. Let's get into what a CPM schedule is, why you might want to use one, and how you can get started right now with our free critical path method schedule template.

What is a CPM schedule?

A CPM schedule is a specific timetable you assign to your CPM-planned project. The goal of planning a project with CPM is to identify the series of tasks (a.k.a. activities) that will take the longest to complete. This series of tasks is called the critical path, and it controls the project duration. If any task along the critical path is delayed, the whole project will be delayed.

CPM scheduling is the act of giving each project activity an early start date, a late start date, an early finish date, and a late finish date. Then, you visualize this timetable with a Gantt chart (or a network diagram) to identify the series of critical tasks that make up the project's critical path.

CPM is a lot to keep track of, so project managers have historically turned to

project management software ⁠

explicitly built for CPM scheduling. This software is typically expensive and designed for the construction industry, where managing subcontractors and dozens of stakeholders is the norm. But free and cheap alternatives have arisen in the recent decades, to the point where project managers from any industry can use tools like Microsoft Excel, Google Sheets, and, yes,

Coda⁠

, to leverage CPM scheduling for their complex project planning needs.

What are the elements of a CPM schedule?

A CPM schedule includes start and end dates for each task, with the goal of identifying the longest path of dependent tasks in the entire project. The longest series of dependent tasks is typically the critical path.

1. Individual project activities

The first component of a CPM schedule is the list of each individual project activity (i.e., project task). Then, assign dependencies to each activity, where one activity must be completed before moving on to the next.

2. Earliest start date

Assign an earliest start date to each activity. This date may depend on the earliest finish date of the preceding activity.

3. Latest start date

Next, assign the latest start to each activity. Like the earliest start date, the latest start date may depend on the latest finish date of the preceding activity.

4. Earliest finish date

Each activity also needs an early finish date, which is your optimistic estimation should everything go well. It's essential to make as accurate an estimation you can for both the earliest and latest finish date (which we'll describe next) because these estimations directly impact overall project completion time and the final project completion date.

5. Latest finish date

Finally, you'll need to assign a late finish date to each activity. The latest finish date is the latest possible date the activity can finish without derailing the entire project.

6. Total float (a.k.a. total slack)

An activity's total float is the range of time between its earliest start date and its latest finish date. Total float is essentially the amount of time you can delay an activity before it interrupts the start dates of other activities. The series of tasks with little to no float is likely the critical path, where each task must finish on time, or else it will throw off the entire project.

7. The critical path

The critical path is typically the longest series of dependent activities (also called critical tasks or critical activities) that control the project duration. Start to finish, this critical path controls the amount of time it will take to finish the project. The project manager should almost always prioritize critical activities when dealing with competing priorities.

What are the benefits of a CPM schedule in project management?

A CPM schedule is best for complex projects, where every stakeholder needs to be aware of the overall project priorities. Specifically, risk management, cash flows, and communication are the three biggest benefits.

Manage project risks.

A CPM schedule is a visual way to prioritize critical actives over other tasks. As the project progresses, the project manager and other stakeholders can proactively identify threats to on-time project completion. In this way, the CPM schedule can become

a risk assessment tool⁠

, helping the entire project team foresee and mitigate project risks.

Maintain better cash flow management.

For big projects, lost time can mean lost money. A CPM schedule can keep all stakeholders on time and help the entire team

avoid needless expenses⁠

Establish a common baseline.

A CPM schedule provides one single, easy-to-understand document the entire project team can reference. One of the biggest hurdles to scheduling projects is keeping everyone aware of the necessary activity deadlines, overall milestones, absolute latest possible finish times, and how to prioritize competing interests. A good CPM schedule can keep everyone aligned on the same priorities.

Best practices for CPM scheduling.

Allow the CPM schedule to reveal what's important.

One of the main purposes of using the critical path method is to reveal what is most important to a project's on-time completion. Your initial strategy may prioritize activities outside the critical path. While these activities are important, they don't have as big an impact on the project's timeline as a critical activity will. In cases like this, don't let your preconceived notions of what activities are most important get in the way of the reality of what activities truly count as critical.

Sequence and link all activities.

All activities should have a predecessor or dependent. If they don't, you run the risk of missing important connections and trends within the overall project. Most importantly, an activity without proper connections might actually turn out to be a part of the critical path, and you won't find out until it's too late.

Create reasonable activity timelines.

One of the trickiest parts of creating a CPM schedule is predicting reasonable start and end dates. If you're debating on dates to assign, always aim for a longer timeframe or later dates (if you have that flexibility) to give yourself flexibility.

Assign people to all activities.

Each activity needs an owner. This team member will manage the activity's float time and ensure it finishes within the correct timeframe. If activities are instead managed by committee (or worse, by no one), you run the risk of miscommunication, negating all the up-front planning you've done with CPM scheduling.

Coda’s Free CPM Schedule Template.

As we mentioned before, CPM scheduling has historically been very complex, requiring sophisticated, expensive project management tools. These days, all you need is a free Coda account.

I have a free CPM schedule template you can use right now if you'd like to test out the method for yourself.

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👉 Get started with this free risk analysis template⁠

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CPM schedule FAQs

What is CPM in project scheduling?

CPM stands for

critical path method⁠

, which is a project management strategy that helps project managers identify a series of tasks (called the critical path) that most directly impact the on-time completion of a complex project. CPM scheduling is applying a timeframe to a project's tasks to identify the critical path.

Is CPM a scheduling technique?

CPM is a project planning workflow, not necessarily a scheduling technique. But, it is very useful in scheduling and prioritizing project activities and deliverables to ensure complex projects stay on schedule.

What is the difference between CPM and PERT?

CPM (Critical Path Method) and

PERT (Program Evaluation Review Technique)⁠

are similar project management strategies. They both aim to identify the most important series of tasks to the on-time completion of a project. The main difference is how they calculate the "total float" (i.e., the time window or activity durations) of an activity. CPM is also typically displayed with a Gantt chart, while PERT uses a network diagram. Check out our

free PERT template here⁠

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