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PERT Chart vs. Gantt Chart: A Comparative View

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PERT (Program Evaluation and Review Technique) charts and Gantt charts are two of the most popular visual project management tools often used for efficiently scheduling and administering tasks necessary to complete a project. But it’s essential to know the differences between PERT chart vs. Gantt chart to get their usage right depending on the nature of the project among other factors.

Projects involve many steps, information, and data for project managers to deal with. This can be a struggle and can cause project delays and going over budget.

Did you know?

Only 29% of projects undergo successful completion on time.

That’s why project management tools are essential to see improved performance on projects. Comparing a PERT chart vs. Gantt chart makes it possible for project managers to plan, visualize, and administer complex projects.

Going forward, we’ll discuss the similarities and differences between the charts while also understanding how you can use these for successful project management.

PERT Chart vs. Gantt Chart

Differentiating PERT chart vs. Gantt chart depends on the timing of their usage as well as their formats. While PERT is used before a project begins, Gantt is used during a project.
But that’s not all there’s to know. There are many differences between the two management tools that not only make them unique but essential as well.

What’s a PERT Chart?

The PERT (Program Evaluation and Review Technique) Chart is used for planning and mapping a project to determine its length.

Project managers often use PERT charts to:

  • break down tasks and responsibilities and simplify complex projects having too many moving parts
  • assess risks and bottlenecks that could be associated with the project and cause delays
  • find out whether a task requires more than one individual working on it and if their work is dependent on another

What’s a Gantt Chart?

Project managers use Gantt charts right from the start to the end of a project. At times, this management tool is also used to break down tasks into subtasks in case of larger projects. The chart is represented via an X and Y axis that depicts the list of tasks and the timeline of the project, respectively.

A Gantt chart has the following features:

  • Displays tasks linearly on a bar chart
  • Displays the anticipated duration of each task within a project as well as its entire timeline
  • Aids in coordinating project resources and scheduling team member responsibilities
  • Provides clear visualization of progress and dependencies to easily identify problematic issues that take too much time and block progress on other tasks

Difference Between PERT Chart & Gantt Chart

The table below elaborately outlines the differences between a PERT chart vs. Gantt chart:

PERT Chart Gantt Chart
The chart was designed during the 1950s by the U.S. Navy to manage complex projects. Henry L. Gantt created the chart in 1917 to aid people in understanding a project’s status at a glance.
Represents the task dependencies, project duration, individual responsibilities, and project status in the form of a flowchart. Represents project data in the form of a horizontal bar chart. This data includes the project timeline, dependencies, as well as the responsibilities of the individuals involved.
Illustrates project events or milestones in the form of nodes (boxes or circles) that are connected via arrows, representing their dependencies. Consists of an X and Y axis. The X-axis depicts task timelines. The Y- axis represents the individual task to be carried out.
A completion percentage can be added to the nodes to represent how much work has been completed. The task completion percentage determines how much a bar has been filled.
Used to build project timelines after the tasks have been defined. As a project progresses, it tracks the status of individual tasks and is used to further break tasks into smaller segments.
Helps in calculating the sequence of scheduled tasks in a project to determine its critical path. Provides a theoretical overview of a project’s timeline.
Best for working on larger and more complex projects where the duration of tasks is doubtful. Can be used to manage projects of all sizes.
Useful for determining interdependence between project plan tasks as well as for measuring the length of the project development process. Essential for identifying bottlenecks in the project development process and aids you in staying on track.
PERT uses a flowchart system. Gantt uses a linear bar chart.
Best used during the planning phase of a project since they allow users to map out the whole scope. More helpful when a project starts because they allow for adjustments as the scope changes.

A close view of the PERT chart vs. Gantt chart formats, as detailed above, can give you a deeper understanding of how each would look if used for the same project.

PERT Chart and Gantt Chart Formats

While PERT charts are different from Gantt charts, they can be used for similar activities. Their appearance and formats differ in some ways though, and it’s essential to understand this so that you can use them correctly.

For instance, let’s take a simple example of a website development project. If we use a PERT chart, it can be visually represented as below.

PERT chart for website development

The white boxes, also called nodes, represent the project milestones. The arrows connecting the boxes represent the link between these milestones. Once a task is completed, you can write the completion percentage inside these nodes.

When converted to a Gantt chart, the same tasks seen above will look as follows. As you can see, the diagram below shows the Y-axis, which enlists each task as a bar spanning across a particular timeline. The timeline is the X-axis, which shows how much time a project will take to finish. The color of the bars is assigned according to the taskā€™s completion level.

Gantt chart for website development

Advantages of PERT Chart Over Gantt Charts

PERT charts are advantageous over Gantt charts for many reasons. Some of the main reasons why project managers choose to work with PERT charts are as follows:

Calculation of Critical Path Method

Unlike Gantt charts, PERT charts can easily calculate the critical path of a project. The critical path denotes the tasks with the longest duration. PERT charts enable project managers to avoid delays and keep projects on schedule by closely monitoring the critical path.

Better Visualization of Milestones & Events

PERT charts are known to be more focused on the tasks, their dependencies, and relationships, unlike Gantt charts which focus more on the overall timeline of a project. Project managers get a bird’s eye view of the project with PERT since everything is clearly laid out in front of them. This also aids in identifying bottlenecks that could cause project delays.

Helps You Set Practical Deadlines

PERT charts are used before starting a project, during the planning phase, to anticipate the duration of each task. PERT charts make use of three types of time estimates, namely-

  • Optimistic- The shortest duration a task might take to complete
  • Pessimistic- The longest duration for a task to be completed
  • Most Likely- The most probable duration for a task to be completed

Using these time estimates, project managers can easily plan projects which have uncertain deadlines for activities. Creating realistic deadlines also makes scheduling resources easy, especially when working on large-scale or complex projects.

Advantages of Gantt Charts Over PERT Charts

Nowadays, project managers use Gantt charts for planning projects and tracking their progress while also allocating necessary resources for them. The basic version of this management tool aids the organization of project tasks via a visual timeline. This helps project managers in mapping out project plans.

However, the management tool has wider applications when it comes to project management. Some of the advantages that Gantt charts have over PERT charts are as follows.

Creates Transparency Across Teams

Gantt Charts adjust according to the progress of a project, updating project schedules on the go in the process. This keeps everyone involved in the project informed about the ongoing developments and their responsibilities toward the completion of the tasks.

In short, we can say that everyone is clear about their role in the project as well as the task they’re meant to complete.

Improves Communication Channels

Project managers can eliminate unnecessary meetings with team members to discuss project requirements and bottlenecks. With Gantt charts, team members can easily understand the progress of tasks as well as any bottlenecks that may arise, which they can discuss and sort out.

Gantt charts, unlike PERT charts, are useful management tools that allow individuals to visualize task deadlines against the overall timeline of a project.

Ensures Efficient Resource Management

Resources are a critical component that determines the failure or success of a project. Gantt charts help project managers with resource forecasting while striking a workable balance for employees, ensuring no one is overloaded with tasks.

Resource forecasting can predict the number of resources that a project would require to ensure its successful completion within a given budget. Gantt charts simplify viewing the availability of resources, based on which project managers can rearrange task timelines and undertakings.

When to Use a PERT Chart vs. Gantt Chart

Both PERT charts and Gantt charts are unique and vital in their own ways to a project manager.
When comparing the PERT chart vs. Gantt chart in terms of usage, the former makes it easy for team members to see which tasks are interdependent and who is responsible for them. The latter, i.e., Gantt charts, are often elaborate and very heavy, requiring team members to take a closer look to get an overall picture.

Below are some tips to help you determine when to use a PERT chart vs. Gantt chart and vice-versa:

When to use a PERT Chart

Project managers can use PERT charts for the following requirements:

  • To find out the scope and necessary course of action for a project
  • To calculate realistic timelines to complete a project
  • To work on major, complex projects
  • To establish dependencies between tasks within the project
  • To keep a close eye on the critical path so that projects can be implemented as planned

When to use a Gantt Chart

Gantt charts can be used when a project has the following requirements:

  • To maintain open lines of communication with individuals, teams, and stakeholders regarding the project’s progress
  • To manage duties transparently among teams and individuals participating in the project
  • To get a bird’s-eye perspective of the entire project and calculate task durations for the effective completion of the work
  • To utilize resources correctly such that they are effectively assigned to the project tasks, thus offering complete visual management. This ensures the maximization and optimization of the resources.
  • To divide projects into smaller tasks and highlight the scheduling constraints
  • To lookout for bottlenecks that could delay project completion

Streamline Project Management With the Right Visual Tools

In conclusion, we can say that both of these visual management tools have their own set of attributes and benefits. Both offer analysis, planning, and scheduling techniques making it difficult to choose one.

Despite their differences, PERT and Gantt charts aim at better project planning and tracking to receive successful results. Also, when used together, they can bring out amazing results in projects. What one lacks, the other fulfills with its advantages.

In the end, it’s all about your needs and goals. So now that you know everything about these charts, you can easily choose the right option for visualizing your project goals. It can be PERT, Gantt, or both, depending on your requirements.

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Namrata Diengdoh

ABOUT THE AUTHOR

Namrata Diengdoh

Namrata is a freelance writer with Replicon. With 12 years of experience in the content industry, she has never settled for just "good enough". She believes in content that can engage and attract readers, whether the niche is fitness, food, or tech. When she is not typing on her laptop, Namrata is crafting or painting. Other than that, she loves spending time with her family and pets.

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