how to read a gantt chart - a project management gantt chart shows project tasks and timelinesProducts like Microsoft Project and Standard Time® offer Gantt charts to show visual representations of project tasks. Gantt charts are optional, but valuable for project management. This article helps you read and understand them. Your project management knowledge will increase by knowing the anatomy of a Gantt chart. They are very easy to read and understand.

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Gantt Chart

Henry Gantt invented the Gantt chart to measure tasks in a project. It measures task duration on a horizontal time scale using graphical bars. The image below is a typical Gantt chart. It shows both summary tasks and normal tasks. Notice the different bar styles.


Tasks are measured against time. In other words, we wish to know how long tasks will take, and when they will start - in graphical form. It is much easier to see the relationships between tasks when we see a picture of them. We can easily see that one tasks starts before another, or that one tasks takes longer. We know this because each task is set against a known time scale. Normally, the time scale will measure days, weeks, months, quarters, or years. You can scroll back and forth through time. Right-click on the scale to change it.


Each bar represents a task. Project tasks are work to be performed. They may be assigned to one or more employees, and usually have a starting time and duration. The start time and duration is placed against the time scale for visual comparison. That lets you see how each task compares with others - all at a glance.

Summary Tasks

Sometimes projects are broken down into phases or sub-projects. We call them subsystems in the program, but you can change that terminology. Microsoft Project calls them summary tasks. No one ever works on a summary task - they work on the actual tasks under them. Summary tasks are used to summarize all the actual work. They help break down a project into manageable parts. These manageable parts are the real tasks.

In a Gantt chart, summary tasks are shown with triangles at each end. This signifies the start and end of the summary. You'll notice these in the Gantt chart above. All tasks under the summary task are included in the summary bar.

Project Tasks

The actual tasks of a project are represented by a rectangular bar. The start dates and finish dates determine the position and length of the bars. This helps us visually compare one task with another, or all at once.

Percent Complete

Inside the task bars is a smaller bar representing the actual work that has been performed on that task. Our system obtains this value from the timesheet -- from the hours entered. As employees enter time into the timesheet, it fills up the percent complete bar in the Gantt chart.

Gantt Column

To show the Gantt column in the Project Task view, follow these steps:

  1. Click the 'Project Tasks' tab
  2. Choose View, Columns
  3. Click the Gantt column in the left-hand column
  4. Click Add
  5. Click Move Up or Move Down to reposition the column
  6. Click OK

After showing the Gantt column, you will see bars representing each project task. The summary tasks will be collapsible, meaning that you can hide the real tasks. When you collapse a summary task, the bars in the Gantt chart will go away as well as the text.


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