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October 07, 2022

The Gantt chart: All you need to know

Gantt Project Management
Jerzy Żurawiecki Content Specialist @BigPicture

The Gantt chart is one of the most impactful project visualization tools of all time. It’s been around for over a century now, so it’s safe to say that it has made itself at home in the world of project management.

It was created with Classic projects in mind. However, you can also use Gantt charts in Agile and Hybrid initiatives. But first, you should know what it is and how you can benefit from using it. Let’s get started, then.

What is a Gantt chart?

The Gantt chart’s definition states that it’s “a commonly used graphical depiction of a project schedule. It’s a type of bar chart showing the start and finish dates of a project’s elements such as resources, planning, and dependencies.”

Gantt charts use bars to visualize the project’s scope on a timeline. As for the dependencies, they are drawn using lines that connect the dependent tasks. Take a look at an example of a Gantt chart below.

An example of a Gantt chart in BigPicture
An example of project visualization using a Gantt chart in BigPicture.


As you can see, a Gantt chart consists of multiple components. Each one has a role to play, so let’s dissect them in more detail.

Key elements of the Gantt chart

Most Gantt chart software contains similar elements of the tool. The six components listed below are the cornerstones of the Gantt chart.

Taskbars

The most visible element of all, the bar, shows the task name and stretches based on its duration. The longer a task takes, the wider it will be on the chart.

It’s not just the tasks, though. The bars also present phases and sub-tasks. After all, a Gantt chart is about visualizing the entire project. Various tools use colors and symbols to differentiate between task types, parent-child relationships, and progress status.

The Gantt chart visualizes the sequence of tasks better than any other tool. The bars are a key reason for that. They allow you to see the duration of each part of the project much clearer than by looking at the start and end dates.

You see the hierarchy of phases, tasks, and sub-tasks, as well as any dependencies between them. As a result, the project becomes easier to grasp in its entirety. The Gantt chart also helps locate the finished and upcoming assignments on a project map.

The task bars highlighted on the Gantt chartTimeline

Time is a crucial component of any project, a must-have metric for planning activities. Monitoring progress is easier when you can see how much time has passed since the project’s beginning or the previous task’s end. That’s why every Gantt chart features a timeline to place the elements of the project in the context of time.

Depending on the project’s duration, most PPM tools allow you to display quarters, months, weeks, or even days on the timeline.

The Gantt chart with the timeline of the project highlighted in red
The Gantt chart with a highlighted timeline.

Milestones

Simply put, a milestone marks an important event in a project. There is no specific action that a milestone has to represent – it depends solely on the project. Managers use milestones in Gantt charts to indicate various occurrences. It can be the end of a project phase, a delivery of functionality, or even a meeting summarizing the completion of a set of tasks.

Most PPM tools use a diamond-shaped icon to symbolize a milestone on Gantt charts. Unlike tasks and phases, it doesn’t have an assigned duration.

A milestone with a diamond-shaped logo marked with all of its dependencies in BigPicture.
An example of a milestone along with dependencies in BigPicture.

Dependencies

Projects contain multiple tasks that need to be done to deliver the intended result. They are organized and planned. In many cases, one task cannot start until another one is complete first. That’s an example of dependency. We can discern four types of dependency relations in project management:

Dependency relations in project management

A Gantt chart visualizes all dependencies in a project. This gives you a clear insight into the connections between the upcoming workload, teams, or specific members.

Look at the comparison of a project phase with and without dependencies below. The top one shows an interconnected network of tasks. The bottom one is just a map of things to do without any information on how each one impacts the other.

That’s why dependencies are so beneficial in project management. They present the entire relationship between tasks. This allows managers to see the bigger picture of the initiative. On top of that, any delay in a task is reflected in the start and end dates of all the dependent elements.

A comparison of the Gantt chart with dependencies turned on and off

Baselines

Think of a baseline as a point of reference for the planned duration of a task or phase. It lets the managers know when a task is supposed to start and finish – aka what the original plan was. Conversely, taskbars show actual duration, so you can compare the two to see whether a task or phase is on track, early, or delayed. In BigPicture, lines under the taskbars represent the baselines, just like in the example below.

An image of a Gantt chart with a baseline highlighted

Work Breakdown Structure

Additionally, most Gantt chart tools present a list of tasks corresponding to the bars visible in the chart. It’s called a Work Breakdown Structure. The phases and tasks are presented as a structured list. Each task in WBS is in the same row as its visual representation on the chart.

The structure expands the range of available information. Most PPM tools give users the option to add columns with additional fields. The most popular include time tracking and cost estimation. Most data points can be modified using in-line editing. This eliminates the need to leave the Gantt chart to update project-related values.

Work breakdown structure in the Gantt Chart
The image shows the relationship between a phase and task and the corresponding Work Breakdown Structure.

Benefits of the Gantt Chart

The chart provides managers with a lot of value. Otherwise, they would use other tools. But what makes the Gantt chart so beneficial in project management? If you’ve ever asked that question, you won’t have to wonder anymore. Here are the five main Gantt chart benefits for managers.

1. Clear visualization of the project

Spreadsheets are great for gathering data. But, if you want to see how the individual elements impact each other, it’s better to map the entire initiative. That’s what Gantt charts are for – to create a roadmap of the project so that it’s not difficult to follow or understand.

Even a quick look at the Gantt chart can provide insights into crucial project information, such as:

  • Task duration,
  • Delays and their consequences,
  • Dependencies,
  • Resources.

A Gantt chart can help managers in their day-to-day activities but also when discussing the progress of the project during presentations. Conveying project-related information is more impactful with visual stimulus than hard numbers.

The tool opens additional possibilities in terms of planning. One of them is the use of the Critical Path. It’s a sequence of tasks that must finish on time to deliver the project within the deadline.

The other useful feature is the what-if scenario. Simply put, you can create an alternative path for your project with a different timeline. This allows you to see what a project would look like in other circumstances.

2. Overview of the entire project

Another perk of using a Gantt chart is the ability to visualize the whole project in one place. The command center presents all stages and activities of the project. It also helps see the wider context and make appropriate decisions. A simple list of tasks might not produce the same effect.

3. Comprehensive view of dependencies

The Gantt chart lets you see all the dependencies between tasks, sub-tasks, milestones, and phases on an interactive board. It’s a much more intuitive solution than going into each task and looking at a list with related issue numbers. In fact, compare the two approaches yourself.

A comparison of dependencies in Jira and BigPicture

The same goes for adding new connections. You can do that on the Gantt chart, so building a network of dependent tasks will take less time, and the result will be visible in a broader context.

4. Support of cross-team alignment

With the entire project mapped out and visualized, the workload and dependencies are much more comprehensible.

Gantt charts shine not only when managers need to make decisions. They also prove their worth when team members need to know who is responsible for tasks related to their own work. The order of work or the predicted completion of surrounding tasks – this type of information helps members cooperate more effectively.

When everyone knows where each person stands, it improves communication within the team. In other words, Gantt charts let members look at how one person’s actions affect the work of others. It’s all about seeing the bigger picture.

5. Easier resource management

Assigning team members based on the information on the Gantt chart means you already have some information at your disposal. The sequence of the tasks, their start and end dates, the dependencies – all that is already available to you as a manager.

When you add resources to the mix, you get more insights. For instance, the number of work hours needed to complete the tasks. Best of all, you can see this metric for each team member or the whole team. That way, you know who is overloaded with work and who is available to take additional part in the project.

Resources on the chart in BigPicture
The Gantt chart combined with Resources in BigPicture


If you haven’t used the Gantt chart before, don’t wait any longer. It’s an invaluable tool for anyone who manages large chunks of work. If you want to visualize a project, track its execution, or oversee dependencies, the Gantt chart will help you out. There is plenty of project management software with its own take on the age-old visualization method. However, if you manage your team’s work in Jira or Trello, BigPicture or BigGantt are your best options.