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What Is A Gantt Chart, And Why Is It Used?

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Let me just come right out and say it. I love me a good Gantt chart. Is that nerdy? If it is, then you’ll be a big huge nerd by the time you finish reading this article, too.

But let me be clear: I said “a good Gantt chart”.

A good Gantt chart tells a visual story about the relationships between the work to be done plotted over a period of time. It shows what has to happen in order for something else to start, or what has to finish for something else to finish. It shows what work will be happening concurrently in a silo and what work will require collaboration. It articulates phases and gives logic to key dates. It takes the complexity of the project and distills it into simplicity. And it shows a viable path to success.

Contrast that against what I consider to be a bad Gantt chart. A bad Gantt chart is the one that only a project manager wants to look at. It regurgitates the complexity of the project onto a page and is about as visually interesting as mold growing on a piece of bread. It’s the story that no one wants to hear because it’s jargony and dull. And because of that, the only inputs to it throughout a project come from the project manager and the project manager alone.

In this article

What a Gantt Chart Looks Like

Designed in the late nineteenth century by mechanical engineer Henry Gantt, the Gantt chart is a project management tool that allows the user to visualize project data quickly. Most prominent of this project data is task dependency and responsibility as well as current project progress. All of this is shown in relation to the established project timeline. In short, like a map of a town, a Gantt chart offers a bird’s-eye view of a project’s steps and progress.

Related: What is Gantt chart software?

Gantt Chart Setup

Any Gantt chart software will create a horizontal bar chart. The vertical axis on the left is composed of the task list that will be completed throughout the course of the project. The tasks are arranged from top to bottom in the order that they need to be completed for the project.

The horizontal axis is a project timeline. The horizontal bars that are created for each project task are proportional to the amount of time needed for each task. If the entire project takes four weeks and the first task is expected to take a week, the bar chart for that task would fill a quarter of the timeline.

Most online Gantt chart software also shows the project manager which member of the project team has been assigned to each task. The amount of the bar that is filled informs the project manager how much progress has been made on each task.

Additional Information in a Gantt Chart

Gantt charts illustrate when members of the project team can begin the next task and when they must wait. The Gantt chart affords the project manager a consistent view of the project’s critical path and overall project progress. By having a visual of this critical path, it is easy to see when scheduling adjustments need to be implemented so as to avoid bottlenecks in the project’s progress.

Related Read: 7 Elements To Include In A Gantt Chart + Other Gantt Chart Tips

Why Are Gantt Charts Used?

The Gantt chart identifies tasks that can be completed simultaneously and those that are dependent upon completion of another task. Because the bar chart is plotted against a timeline, a Gantt chart might also reveal where downtime exists in the project. Project managers must find these inefficiencies and adjust the resource plan, timeline, or critical path to ensure optimal resource utilization.

Benefits of a Gantt Chart

The Gantt chart template is designed to organize essential project data in one place. Having such crucial information in one chart simplifies planning and makes it easier to estimate the time needed to complete both individual tasks and an entire project.

If updated consistently, even a simple Gantt chart can also replace time-consuming meetings and status updates. Any member of the project team can quickly see the project’s progress.

Items to Keep in Mind

When using this type of project management software, you will need to have a project plan that lists all of the individual tasks required for your endeavor. It is also necessary to have an estimate of how long each task may take. Start and end dates should be established as well. Project milestones can serve as motivation for the project team.

Like with any project management software, the user must provide as much input as possible. The project manager must then understand the terminal elements of the entire project and know the project’s work breakdown structure. No Gantt chart tool will tell you a specific task is missing or who on your team should do what.

Best Uses for Gantt Charts

Project management needs tools like Gantt charts because they can be used to manage all types and sizes of projects. The Gantt chart template has been around for decades, and as such it has been used to manage the work breakdown structure in the building of such infrastructure as dams, highways, and bridges.

Today, the modern Gantt chart is used throughout the technology sector, which is evidenced by the myriad Gantt chart software that has been created.

Project managers utilizing the Waterfall methodology typically prefer Gantt charts. Since the Waterfall model deals with a project schedule sequentially, the Gantt chart is ideal for visually mapping this sequence.

Furthermore, this project management chart provides managers with a visual way to divide their project into manageable chunks. This tool also helps them identify milestones within a project’s timeline, which gives them data they can use to provide feedback to an organization’s stakeholders.

Overlooked Uses of Gantt Charts

Because a Gantt chart illustrates task dependencies and a project’s critical path, this project management tool can show how changing one individual task can potentially impact the entire project. Successful project management often requires the ability to be agile, so foreseeing how a change now will affect a project’s completion in the future is essential. This type of feedback is one of the underused elements of a Gantt chart.

Limitations of Gantt Charts

No project management software is perfect. Neither is the Gantt chart—it can become too complex as the number of dependencies and activities increases. In other words, an overly stacked bar chart can include so much detail that the overall impression is confusing.

As a project increases in complexity, a Gantt chart can also become overly time consuming. This is especially true for a smaller business that doesn’t devote any single employee solely to the task of project management. Bigger enterprises that employ one or more project managers will be more successful in using complex Gantt charts to their advantage.

Here are a few important omissions from Gantt charts.

Task Priorities

Since a traditional Gantt chart typically lists a project’s tasks sequentially, the chart does not accurately portray a task’s priorities. In a traditional Gantt chart, each task appears as important as all the others, which may not be an accurate reflection of the project’s process.

Required Resources

Although it is essentially a bar chart, the size of the bar for each task corresponds to time, not to the resources required to complete the task. Task management may need to see such information because some planning decisions may need to be based on resources more than time.

Project Costs

Another limitation to the Gantt chart is its emphasis on a project’s timeline instead of cost. Project management often requires cost to be a factor in decision-making, and a Gantt chart will not provide any data to help make this type of decision.

Complete Project View

The project management software that creates Gantt charts often breaks the charts into segments. This makes seeing the entire project on a single screen or a single piece of paper difficult, rendering these charts ineffective for sharing with an audience. In short, there can be so much information on a Gantt chart that the entire project is not viewable at one time.

Other Project Visualization Methods

Successful project management often comes through utilizing multiple tools. Besides a Gantt chart, a PERT (program evaluation review technique) chart can also be useful. A PERT chart focuses more on the dependency between tasks than on a timeline, which makes them useful for managing larger-scale projects.

A network diagram is useful for visually representing how the components or tasks of a project interact, which a Gantt chart is not going to display.

There are also project management tools like Kanban boards that work by assigning story points as opposed to setting timelines.

Final Thoughts

The Gantt chart has enjoyed decades of success as a project management tool because ultimately it is a user-friendly way to visualize the tasks and time needed to complete a project. When utilized with other project management tools, the Gantt chart can provide a wonderful map for tracking the progress of a project.

Find the right Gantt chart software for your project needs here:

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By Galen Low

I am a Client Services Professional and Agile Delivery Specialist with progressive experience driving human-centered digital transformation in government, healthcare, transit, and retail verticals. I manage large, cross-functional teams and executive-level relationships within boutique agencies and large consultancies to drive tangible business outcomes and strategic growth. A few of my specialties: digital strategy, agile web application development, project management, human-centered design, design thinking, innovation & growth, digital government, career coaching, professional development.

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