What is a Gantt chart?


A Gantt chart is a graphical representation of activity against time.

Definition from APM Body of Knowledge 7th edition  📖


A Gantt chart is a project management tool assisting in the planning and scheduling of projects of all sizes, although they are particularly useful for simplifying complex projects. Project management timelines and tasks are converted into a horizontal bar chart, showing start and end dates, as well as dependencies, scheduling and deadlines, including how much of the task is completed per stage and who is the task owner. This is useful to keep tasks on track when there is a large team and multiple stakeholders when the scope changes.

As it's in a bar chart format it is possible to check on progress with a quick glance. You can easily see:

  • a visual display of the whole project,
  • timelines and deadlines of all tasks,
  • relationships and dependencies between the various activities,
  • project phases

Project management solutions that integrate Gantt charts give managers visibility into team workloads, as well as current and future availability, which allows for more accurate scheduling. Gantt charts have been around for nearly a century, having been invented by Henry Gantt, an American mechanical engineer, around 1910.

History of the Gantt chart

It is difficult to envisage how a modern project would be managed without at some point creating a chart of tasks to be done in delivering the project’s declared benefits. One of the most enduring types of chart is the Gantt chart.

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How to use a Gantt chart

The underlying concept of a Gantt chart is to map out which tasks can be done in parallel and which need to be done sequentially. If we combine this with the project resources we can explore the trade-off between the scope (doing more or less work), cost (using more or less resources) and the time scales for the project. By adding more resources or reducing the scope the project manager can see the effect on the end date.

To create a chart you need to know all of the individual tasks required to complete the project, an estimate of how long each task will take and which tasks are dependent on others. The very process of pulling this information together helps a project manager focus on the essential parts of the project and begin to establish a realistic timeframe for completion.

In summary:

  • When you set up a Gantt chart, you need to think through all of the tasks involved in your project and divide them into manageable components.
  • Then decide who will be responsible for each task and delegate to the team.
  • Identify task relationships and decide on the completion date sequence for each task, showing the expected time duration of the whole project and the sub tasks. A Gantt chart will show the tasks in a sequential order and display task dependencies (ie. how one task relates to another).
  • Determine and allocate your resources.
  • Anticipate the risks and problems you may encounter and create a contingency plan for potential problems.

Planning, scheduling monitoring and control

This book offers practical guidance on all planning aspects of preparing to undertake a project, executing a project, controlling its delivery to budget, time and quality, and delivering it safely.

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Why use a Gantt chart?

A Gantt chart is used for the following activities:

  • Establish the initial project schedule - who is going to do what, when and how long will it take.
  • Allocate resources - ensure everyone knows who is responsible for what.
  • Make project adjustments - the initial plan will need many adjustments.
  • Monitor and report progress - helps you stay on schedule.
  • Control and communicate the schedule - clear visuals for stakeholders and participants.
  • Display milestones - shows key events.
  • Identify and report problems - As everything is depicted visually you can immediately see what should have been achieved by a certain date and, if the project is behind schedule, you can take action to bring it back on course.

Possible downfalls:

As Paul Naybour explains in his blog, Gantt charts are not perfect and can become overly complex with too many dependencies and activities. It is better to produce a clear and simple plan that shows the main work packages in summary, than a plan with so much detail that the overall impression of project progress is lost. 

Gantt charts are also not good at showing the relative priorities of individual tasks and the resources expended on a task. They can clearly show the elapsed time of a task but don't easily communicate how many people may be needed to complete it. This is where using additional techniques such as a precedence diagram (sometimes called a PERT chart), for instance, becomes useful.

APM Body of Knowledge

The APM Body of Knowledge 7th edition provides the foundation for the successful delivery of projects, programmes and portfolios across all sectors and industries.

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Make your own Gantt chart in Excel

Microsoft Excel has a Bar chart feature that can be formatted to make an Excel Gantt chart.

  • Step 1. List your project schedule in an Excel table. List each task as a separate row and structure your project plan by including the start date, end date and duration.

  • Step 2. Set it up as a standard bar chart based on start dates.

  • Step 3. Add the duration of your tasks.

  • Step 4. Add task descriptions to the Gantt chart.

  • Step 5. Transform the bar graph into the Excel Gantt chart through formatting.

For step-by-step instructions see the full article. You can also do this in Powerpoint, suitable for presentations.

Microsoft has an Excel Gantt chart template which you can download

Starting Out in Project Management

Written for anyone new to projects or wishing to progress their career, Starting Out charts the journey of the APM project life cycle, from concept through to delivery and handover.

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What is project management?

Project management is the application of processes, methods, knowledge, skills and experience to achieve the project objectives. 

Projects are the vehicles of change in an organisation. They are not the repetitive business-as-usual type of activity.

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Agile Project management 

Agile project management is an approach based on delivering requirements iteratively and incrementally throughout the project life cycle. 

At the core of agile is the requirement to exhibit central values and behaviours of trust, flexibility, empowerment and collaboration

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APM Library

APM's library is a dedicated project management resource to help you on your journey to becoming a professional project manager.

It contains free downloads of reports, case studies and white papers.

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