Gantt Chart

Definition of the Gantt Chart

The Gantt Chart or Gantt Diagram is a tasks planning tool used in project management. Developed and popularized around 1910 by Henry L. Gantt, this tool is used to model and easily display tasks planning of a given project.The Gantt Chart is widely used by project managers whatever their activity is.

Advantages of the Gantt Chart

The Gantt Chart allows:

• To show the progress of a project’s tasks in a simple and concise way,
• To plan project’s needs in human and material resources,
• To help in the project’s budget establishment,
• To follow project’s costs: consumption of human resources D/m, equipment …
• To communicate simply on the project’s progress. 

Example of a Gantt Chart

Construction of a Gantt Chart

A simple spreadsheet tool like Excel or the free Calc from OpenOffice can be used to build a Gantt Chart. However, there are various specific tools like Microsoft Project, to quote only the most known of them, but also free “MS Project like” softwares like Ganttproject 

Tasks

A Gantt Chart is organized like a matrix or a table where every line represents a task to be realized while columns represent the timescale: days, weeks, month … 

The estimated duration of a task is modeled by a colored horizontal bar going from forecast beginning date up to forecast finish date of realization.Tasks can be made at the same time or one after the other.

Every task can be linked to other tasks: a task B cannot begin before the task A finishes. This type of link is graphically represented by an arrow going from task A towards task B. 

The actual progress of every task can be reported in percentage of the task’s forecast duration and is graphically represented by a bar of different color inside every task’s bar. The project manager only needs to draw a vertical bar on today’s date to see which tasks are in advance, on time or late. 

Milestones

On a Gantt Chart, one can display important milestones of the project as the writing of the specifications, the signature of the contract, the decision of the steering committee… They will be used as references by the project manager.

A milestone is in fact, a task which duration would be equal to zero, generally represented by a full rhombus.

Resources

For every task, the user can input necessary resources (human & material) to its achievement.

This function is very useful for the project manager who is going to be able to:

• Forecast his or her needs in terms of staff,
• Forecast his or her budget,
•  Follow the activity of every resource, human or material.