Critical Path Method in Project Management: How To Use It?

Read it in 16 Mins

17th Apr, 2023
Critical Path Method in Project Management: How To Use It?

You can better visualize what steps need to be taken to accomplish your objective by creating a project plan. You're aided in doing it via the critical path method in project management. It is a method of project management that entails outlining the crucial actions that must be carried out to finish a project. By utilizing this method, you may manage work dependencies and establish reasonable deadlines. Learn how the critical route approach functions and how you can apply it to projects with your team by reading it. 

What is the Critical Path Method in Project Management?

The Critical Path Method (CPM) in project management is a straightforward but effective method for planning, scheduling, and assessing big, complicated projects. It is used to identify a project's critical path or the longest list of tasks that must be done before the entire project can be considered finished. 

Critical Path Analysis (CPA), another name for CPM, demonstrates how interdependent tasks are and which tasks are essential to a project. 

One of the key ideas in project management, and undoubtedly one of the most enduring, is the Critical Path Method (CPM). You may learn about the Critical Path Method and use it in your projects with the aid of this user-friendly technical project manager certification. 

CPM was created in the late 1950s to address the problem of rising costs brought on by ineffective scheduling. Since then, CPM in project management has gained popularity as a tool for organizing work and planning projects. It enables you to deconstruct challenging projects into manageable jobs and improves your comprehension of the project's flexibility. 

Critical Path Method and Critical Task

No matter how big or how expensive a project is, it must always complete a few fundamental duties. A task is deemed crucial if postponing it may delay the project's completion. Consider something basic like preparing pasta. 

The following would be a brief recipe for preparing pasta: 

  1. Boil pasta shells in salted water. 
  2. Heat a pan and add butter/oil when hot. 
  3. Add pasta and cook for some time. 

There are several other tasks you need to perform to make good pasta. Maybe add some vegetables and some cheese. Perhaps you could flip it on the other side, so the pasta is fully cooked through. 

But in addition to the recipe's three essential steps, these actions are also involved. You'll still have pasta even if you choose not to perform them. Even though it's not very excellent, pasta. 

The only thing you'll have, though, is a cold pan and raw pasta if you forget to boil the pasta or heat the pan. In other words, the three steps in the recipe outline the essential duties required to complete the project successfully and produce pasta. 

Critical and Non Critical Tasks

How to Find the Critical Path?  

By comparing the lengths of critical and non-critical tasks, one can identify the critical path. Examples of each stage are shown below. 

1. List your activities  

A work breakdown structure can be used to compile a list of all the project activities and tasks necessary to create the deliverables. The remainder of the CPM is built upon the list of activities in the WBS. 

List of Activities in WBS

As an illustration, suppose the education department is creating a fresh interactive blog article. These are some of the tasks that might be included in the WBS:  

Task IDTaskDuration (in days)
ADraw up a plan1
BCreate a draft3
CEdit the draft before submitting it.2
DGraphics for design posts5
EVisuals can be animated2
FPut up articles1

Starting to identify task dependencies is possible once you have a general understanding of everything that needs to be done. 

2. Identify Dependencies

Select the jobs that are interdependent based on your work breakdown structure. You can use this to find any job that can be completed concurrently with other tasks. 

Following the example from above, these job dependencies are: 

  • A is required for Task B. 
  • B is required for Task C. 
  • It is possible to simultaneously complete tasks C and D. 
  • D is required for Task E. 
  • C, D, and E all affect Task F. 

The critical path will be established using the list of dependent tasks, also known as an activity sequence. 

3. Create a network diagram  

The process of creating a network diagram, a flowchart that shows the sequence of events, using the work breakdown structure, is the next step. To show the dependencies between tasks, make a box for each one and add arrows to it. 

Prior to determining the overall project schedule, you will add additional time-bound components to the network diagram. 

4. Estimate task duration

You must first determine how long each activity will take to compute the critical path, which is the longest series of critical tasks. 

Try the following to gauge the time: 

  • Based on expertise and understanding, making intelligent assumptions 
  • Using data from earlier projects to estimate 
  • Using industry norms as a guide when estimating 

You could also attempt the forward pass and backwards pass method. 

5. Calculate the critical path

Even while it is possible to determine the critical path manually, it is faster to use a critical path algorithm. 

To determine the critical path manually, follow these steps: 

Step 1: For each activity, note the beginning and ending times. 

  • The duration of the first activity is its start time, which is 0, and its finish time. 
  • The prior activity's end time serves as the start time for the subsequent one, and its finish time is the sum of the two. 
  • For each activity, repeat the process. 

Step 2: To calculate the length of the complete sequence, look at the final activity's end time. 

Step 3: The critical path is the set of tasks that take the longest to complete. 

Here is how the critical path diagram may appear using the same example as above: 

Critical path diagram

The real project schedule can be constructed around the critical path after it has been identified. 

6. Calculate the float

A task's slack sometimes referred to as float, indicates how adaptable it is. It illustrates the amount of time that can be added to the task without influencing other tasks or the project's deadline for completion. 

Determining the float helps determine how flexible the project is. Use the resource known as a float to cover project risks or unforeseen problems. 

Since critical jobs have 0% float, their due dates are fixed. Positive float values designate tasks that belong on the non-critical path, where their postponement won't have an impact on when the project will be finished. Non-essential tasks could be skipped if time or resources are limited. 

It is possible to manually calculate the float or use an algorithm. To figure out the total float and free float, use the formulae from the section below. 

Total float vs. Free Float 

Total FloatFree Float
This is the length of time that can pass since the early start date of activity without postponing the project's completion date or going against a schedule constraint.This refers to the maximum amount of time one activity can be postponed without negatively affecting the one after it. Free float is only possible when two or more actions have a single successor. This is where activities come together on a network diagram.
Total float = LS-ES or LF-EF.Free float = ES (next task) - EF (current task)

Project managers gain from having a thorough understanding of float for the following reasons: 

  • It ensures that projects finish on schedule: By allowing you to check the total float of a project to see if it is on schedule. Your chances of finishing early or on schedule increase with the size of the float. 
  • It lets you choose priorities: You'll have a better understanding of which chores should be given priority and which ones have more room for a postponement if you can identify the activities with free float. 
  • It's a helpful tool: Float is additional time that can be used to address project risks or unforeseen problems. You can decide how to use your float most effectively by being aware of how much of it you have. 

A Step-by-Step Process for Using Critical Path Method

CPM model in project management gives you insight into the status of your project and enables you to keep track of activities and their turnaround times. Here are some additional uses for CPM. 

Tighten up the timetables

Project deadlines might occasionally be pushed forwards, which is not ideal. The schedule compression methods of fast-tracking and crashing are both applicable under certain circumstances. 

  1. Fast tracking: Evaluate the critical path to identify tasks that can be carried out concurrently. The overall duration will decrease as more parallel processes are run. 
  2. Increasing resources is a step in the process of "crashing" operations. Make sure the additional resources will still fit inside the project's scope before acquiring them and inform the stakeholders of any modifications. 

Having the critical path diagram can aid in selecting the best tactic to fulfil revised deadlines. 

Overcome a lack of resources

Remember that the CPM method in project management does not account for resource availability. You can employ resource leveling approaches to address resource issues, such as a team member who is overbooked or lacks equipment. 

These strategies are meant to address resource overallocation problems and guarantee that a project can be finished with the resources that are currently on hand. 

Resource levelling affects project start and end dates, thus you might need to modify the critical route or use this method for activities that have floated. 

Gather information for later use

Since you're working with informed estimations for activity durations, the schedule generated by CPM in software project management is liable to alter. As the project progresses, you can contrast the original critical path with the current critical path. 

Future studies can utilize this information as a guide to predict work durations more precisely. 

Critical path method example: 

  1. Reduce delays: By determining the most crucial order of work for a project using the Critical Path Method. Employing this knowledge, managers can streamline tasks along the crucial path to cut down on delays. 
  2. Create a visual representation of dependencies: The CPM relies on a list of all project-related tasks and their dependents. You may visualize all dependencies and order tasks in accordance with the chart you've made. 
  3. Organize better: The CPM aids in the division of work into sequences and deliverables into sequences in complex projects. Project organization is much enhanced by doing this, as well as focusing on visualizing dependencies, mapping constraints, and establishing the essential route of tasks. 
  4. Enhance productivity: Project managers can better understand the significance of each work by mapping the critical route. By adding or withdrawing resources according to the significance of the work, they can more effectively distribute resources. 
  5. Calculating the float: The float describes how much work can be postponed without having an adverse effect on the project schedule, as we'll see later. This plays a significant role in the Critical Path Method. You can allocate resources more skillfully by computing the float. 

Key Terms in Critical Path Method 

It’s important to understand and get up-to-speed with the terms that are used by project managers who are working on this method. Here’s a ready reckoner:  

  1. Schedule refers to the entire roster of activities that are a part of the project along with the time it takes to finish each activity.  
  2. Duration is the estimated time it takes to complete a particular activity.  
  3. Activity-On-Node (AON) is a visual representation of the schedule showing how activities are linked to each other.  
  4. Critical path is the longest chain of activities in the project.  
  5. Critical Activity is any activity on the critical path. The activity is considered critical because a delay in that activity will cause a delay in project completion.  
  6. Early Start (ES) is the earliest date a particular activity can be started on.  
  7. Early Finish (EF) is the earliest date an activity can be completed on.  
  8. Lag is the estimated time to wait before an activity can start.   
  9. Late Start (LS) is the latest date the activity needs to be started by, without delaying the project completion.   
  10. Late Finish (LF) is the date an activity needs to be finished by, without delaying the project.   
  11. Predecessor is an activity that precedes the current activity.  
  12. Successor is the activity that comes right after the completion of the current activity.  
  13. Free Float (FF) is the maximum number of days an activity can be delayed, without delaying a succeeding activity.  
  14. Total Float (TF) is the maximum number of days an activity can be delayed, without causing a delay in the project completion date. 

Become a project management expert with best PRINCE2 course. Take control of your projects and achieve unprecedented success!

Importance of Critical Path Method 

Critical Path Method is a tried and tested way of managing projects. It has been in use for over 60 years, and has been proven to help project managers to smoothen workflows, ironing out any obstacles to progress. helps project managers to:  

  • Prioritize activities  
  • Identify activities that can run simultaneously  
  • Optimize resource allocation  
  • Track progress in real time  
  • Comply with deadlines  
  • Simplify dependencies  
  • Get a wide, bird’s-eye perspective on all project activities 

Top Cities where Knowledgehut Conduct Project Management Certification Training Course Online

Project Management Courses in LondonProject Management Courses in Singapore
Project Management Courses in MelbourneProject Management Courses in Toronto
Project Management Courses in SydneyProject Management Courses in Perth
Project Management Courses in BangaloreProject Management Courses in Dubai
Project Management Courses in MumbaiProject Management Courses in Brisbane

Tools and Software to Calculate Critical Path

There are a few tools or methods that are popularly used to find the Critical Path in a project.   

Activity On Node (AON):

Is a method that represents activities in a diagram to show interdependencies between them. Once durations, early start date, and early finish date are assigned, the critical path can be mapped by using the earliest start date for each activity. This technique is called Forward Pass.   

Using the Latest Start date and Latest Finish Date and starting from project completion, you can calculate the critical path through a similar technique called Backward pass.  


Charts are used for simpler projects where activities are represented in a bar chart format instead of a network chart. This is an alternate method of finding the critical path in a project.  

Gantt Chart

PERT or Program Evaluation and Review Technique:

Works based on a similar principle to other methods. It dismisses the notion that there is a fixed amount of time for an activity to be completed. Instead, it estimates a best-case scenario, worst-case scenario, and an ordinary scenario to estimate the amount of time each activity takes. It calculates variance and standard deviation to see which activities are likely to risk delaying the project by exceeding the time they are estimated to take.   

PERT is a more dynamic method that is more suitable to make flexible project plans as it accounts for the fact that time taken for activities cannot be estimated or predicted accurately. 

Parts of PERT Chart

Software for calculating Critical Path

The calculations can seem complex and if done manually it may end up being a time-consuming exercise. Thankfully, project management software come with options to calculate the critical path.  

MS Project, Wrike, Capterra, Mavenlink, Buildertrend, and WorkflowMax, among others, have features that help the user to identify and monitor the critical path in their projects and keep an eye on activities that are nearing the maximum delay, threatening to derail the project deliveries. 


Planning activities and managing resources are two areas where CPM can be an advantage in project management. You will find it simple to make timetables and keep track of tasks with the aid of project planning tools. You can learn more on PMP certification course online and get certified through KnowledgeHut project management trainings. 

Frequently Asked Questions (FAQs)

1. What is critical path method example? 

CPM project management example: 

For instance, if you were building a house, there would be multiple task sequences like these: 

  • The time and materials needed for each task vary. 
  • Wall construction and roof construction take longer than faucet and fixture installation. 

2. What is the critical path formula?

  • List all of your activities or tasks, making note of their durations and connections. 
  • Create a schedule network diagram, which shows the relationships between your tasks in a visual manner. 
  • Determine all feasible routes across the diagram, then sum up the times required for each activity to determine how long it will take to accomplish each route. 
  • Your critical path is the one with the longest overall duration. 

3. What is the importance of critical path method in project planning?

When managing a project, using the critical path technique is crucial because it helps you identify all the tasks that are required to finish the project, establish which ones must be completed by a certain date, which ones may wait if necessary, and how much float or slack you have. 

4. What is the purpose of critical path?

The purpose of critical path in project management is: 

The longest path from Start to Finish in terms of time is known as the critical path and it shows how long the project must last to be completed. 

5. What are the benefits of critical path method? 

When planning their time and resource allocation, project managers can count on the critical route method. The benefits of CPM include increased scheduling flexibility and accuracy, greater stakeholder and project manager communication, and simpler work prioritization. 


Geetika Mathur


Geetika Mathur is a recent Graduate with specialization in Computer Science Engineering having a keen interest in exploring entirety around. She have a strong passion for reading novels, writing and building web apps. She has published one review and one research paper in International Journal. She has also been declared as a topper in NPTEL examination by IIT – Kharagpur.

Share This Article
Looking for the top courses in project management?

Avail your free 1:1 mentorship session.

Your Message (Optional)

Upcoming Project Management Batches & Dates

NameDateFeeKnow more