What Is a Gantt Chart?

A Gantt chart is a bar chart of a project schedule. Each task gets its own row, with the task names listed down the left, and a horizontal bar beside each name runs from the day the task starts to the day it ends along a shared date axis. Reading across a row tells you when one task happens; reading down the chart tells you what is happening at the same time.

Here is a small website launch plan drawn as a Gantt chart:

Four tasks run from March to May, Build is the longest of them, Testing starts before Build is finished, and the diamond on May 26 marks the launch.

The parts of a Gantt chart

• Tasks. The rows. Each one is a piece of work, listed in roughly the order it starts.
• Date axis. The scale across the top, in days, weeks or months depending on how long the project runs.
• Bars. One per task. Where a bar starts and ends shows the task's dates, and its length shows how long it takes, so long tasks stand out at a glance.
• Dependencies. Links between tasks that can't start until another one finishes, such as Design waiting for Research. They are often drawn as arrows from one bar to the next.
• Milestones. Single dates that matter, such as a launch or a deadline, drawn as a marker instead of a bar.
• Progress. Many charts shade part of each bar to show how much of that task is complete.

Only the first three are needed. The rest are added when the plan calls for them.

Where the name comes from

The chart is named after Henry Gantt, an American engineer and management consultant who designed it around 1910 to 1915 to track the work of factory employees. He wasn't the first. A Polish engineer, Karol Adamiecki, had devised a similar chart he called a harmonogram in 1896, but he published it only in Polish and Russian, so few people outside those countries saw it.

One of the first large uses of Gantt charts was by the United States during World War I. They were drawn by hand for decades after that, and personal computers made them easy to create and redraw from the 1980s on. Today almost all of them are made with software.

What Gantt charts are used for

A Gantt chart answers the questions people ask about a plan: what happens when, how long each piece takes, and when it will be done. That makes it useful for:

• Planning a project before it starts, to see whether the dates add up
• Showing a schedule to a client, a manager or a team in one picture
• Tracking progress once the work is underway
• Seeing what a delay to one task will push back

Software and website projects, construction, events, marketing campaigns and product launches all use them. Our Gantt chart examples show six plans like these with their tasks and dates.

Advantages and limitations

The main advantage is that a Gantt chart is easy to read. Anyone can see the order of the work, which tasks overlap and which ones are long, without knowing anything about how the plan was made.

The limitations come from the same simplicity. A chart with hundreds of tasks is hard to read, so large projects are usually summarized by phase. The chart shows dates but not effort, so two bars of the same length may involve very different amounts of work. And it is only as accurate as its last update: when the plan changes and nobody redraws the chart, people keep planning around dates that are no longer true.

Gantt chart vs timeline

Every Gantt chart is a timeline, but not every timeline is a Gantt chart. A timeline lets events share rows and suits a record of what happened, such as a history or a legal chronology. A Gantt chart gives each task its own row and suits a plan for work that is still to come. See Gantt chart vs timeline for how to choose between them.

How to make a Gantt chart

You need a list of tasks, a start and end date for each one, and an idea of which tasks depend on which. Our guide to how to make a Gantt chart walks through those steps with the plan above as the example.

Excel, Google Sheets, PowerPoint and Word have no Gantt chart type, but each can draw one with a stacked bar chart. See our guides for Excel, Google Sheets, PowerPoint and Word.

In Preceden you type the tasks and their dates and it draws the chart for you. You can make a task start when another one ends, shade a bar by its percent complete and mark any event as a milestone. Our guide to creating Gantt charts covers each of these.