A Gantt chart, commonly known as a bar chart, is a graphical chart. Gantt charts are used to help organize, schedule and monitor project progress. Gantt Charts are named after Henry Gantt who, in the early 1900’s, refined the bar chart into a project management tool.
A Gantt chart is formatted into three areas of rows and columns. The project’s separate activities are listed down the first left column of the chart with each activity in a separate row. The next column lists the duration of each activity in hours or days. The remaining space of the Gantt chart is divided into equally-sized columns that represent time intervals for the duration of the project. Typically, the time intervals are days, with thicker column lines representing weeks and months. If a project is shorter, the individual time interval may be hours instead of days. For each activity, a hollow horizontal box is drawn on the same row as the activity across the time intervals columns in which that activity occurs. The result is a series of horizontal bars tracking down and across the Gantt chart’s time interval columns.
Organizing activities on the Gantt chart is done by deciding which parts of the project need to be scheduled and monitored. An activity should be an identifiable task that is measurable, with a specific start and end date or time. Activities should be broad enough to not overload the chart with tasks, but specific enough to be important to the project’s result.
Next decide which activities can happen at the same time. Organize the activities by relationship – which things have to happen before other activities. Keep the relationship activities sequenced together so that they are scheduled in the right order. Once the activities are identified and organized, list them logically on the Gantt chart. Draw a hollow horizontal bar for each activity from the activity’s start time line to its finish line. After all the activities and bars have been placed, the chart is ready. Monitor the project’s progress by filling in each bar as the activity progresses. Adjust the bar length over the appropriate number of time intervals if the activity takes longer or shorter than planned.
A Gantt chart is a management tool that is easily understood, but it is not a substitute for good project supervision. Simple Gantt charts can be done manually, or on spreadsheet software. For more complex projects, specialized project scheduling software is available.