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What is a Gantt Chart?

Gantt chart
Gantt charts help monitor a project's progress.
Credit: Paul Barnwell | Shutterstock

Gantt charts, or Gantt diagrams, are project management tools used to analyze and plan projects. A Gantt chart is a graphical representation of the progression of time against the duration of tasks and is helpful when monitoring a project's progress. Simply put, a Gantt chart is a bar graph that illustrates a project's schedule, including the start and finish dates of project elements.

Developed in 1917 by Henry L. Gantt, an American engineer and social scientist, the Gantt chart is a horizontal bar chart designed to track specific tasks in a project. Simple Gantt charts can be created on graph paper, or more complex automated charts can be created using project management apps, like Microsoft Project, SharePoint or Excel. Gantt chart templates can be found online. The top three online project management tools for small businesses are Clarizen, AtTask and Tenrox, according to our sister company, TopTenREVIEWS. The monthly costs for these tools are $24.95, $39.95 and $38.95, respectively. [Read full review]

Gantt chart
A Gantt chart showing a simple one-week plan.
Credit: John T. Takai | Shutterstock

When planning a Gantt chart, certain activities are dependent on other activities being completed first. Known as "sequential" or "linear" tasks, these need to be completed before other tasks can begin. An example would be the creation of collateral – it needs to be done before the distribution of collateral can begin. Other activities that don't have to be done in a specific sequence are "parallel" tasks. While they don't have to be done in a specific order, they may sometimes need other tasks to be completed first.

Before drawing up the chart, create a list of all activities in the plan, the estimated length of time it will take, and whether it is parallel or sequential. Show which stages they depend on. It's best to do this using a table, so that your tasks are kept organized.

Now you are ready to draw up the chart. A Gantt chart includes a horizontal axis representing the time span of the project, broken down into increments of days, weeks, or months. The vertical axis represents the tasks needed to be completed for the project. The horizontal bars of varying lengths represent the time span for each task. For example, if preparing a proposal, the first task may be "conduct research," which would go at the top of the vertical axis. Draw a bar on the graph that represents the time you expect the research will take.

Gantt chart
A Gantt chart showing a four-phase, four-week project plan.
Credit: John T. Takai | Shutterstock

Enter the other tasks below "conduct research," and draw representative bars for the time you expect to spend on them. Bar spans may overlap. For example, you may conduct research the same time you are deciding on a budget, and those bar spans will overlap. With the Gantt chart completed, you can now check the resourcing of the various activities and the timeline to make sure that the project itself is doable. The Gantt chart provides a big picture look at the project and gives an overhead perspective for the project managers.

As the project continues, different colors, arrowheads, or other markers can be added to indicate the status of tasks, such as partially or fully completed. With the Gantt chart, users can easily monitor the project's progress. It's easy to see what should have been achieved at any given point in time, and if tasks are projected to miss deadlines, remedial action can be taken to bring the project back on course.

One major problem with Gantt charts is that they don't indicate task dependencies. If one task falls behind schedule, how will that affect other tasks? The PERT chart, another project management charting tool, is an alternative designed to do so. Automated Gantt charts, created with software, generally store more information about the tasks. With programs like this, Gantt charts can include the individuals assigned to each task, notes about the procedure, and enables the user to easily change the chart. The Gantt chart is a dynamic tool – expect that the charts get adjusted frequently to reflect the actual status of project tasks as projects rarely stay with the original plan.