What is a Gantt chart?
A Gantt chart is a project management tool that shows a progression of tasks across an overall timeline for a project—resembling a bar chart. On the left, there is a list of tasks or events that run down the page. Across the top, there is a timescale that runs the length of the project. Tasks are allotted a time frame, and then a bar is constructed for it (with the start and end date of that task being the bar).
There are a variety of ways the chart can be personalized or can include extra information. Different colors can be used for different project phases. Labels can be added to allocate the correct division or resource. Arrows can be added to show interdependence between tasks. And, once tasks are complete or underway, the color of the bar can change to reflect that.
The Gantt chart was first created in the mid 1890’s by Polish engineer, Karol Adamiecki, who called it a harmonogram. He ran steelworks in Poland and was interested in project management techniques. Fifteen years later, an American engineer, Henry Gantt, created his own version of the chart and made it popular.
Now, Gantt charts are used worldwide and are an accepted way to track project timeframes.
Why use a Gantt chart?
A Gantt chart is an exceptional way to show a range of important information:
- The entire length of the project
- Every task within that project (or within that stage of the project)
- How long each task will take
- Which tasks overlap
- How the tasks relate to each other
More importantly, the Gantt chart is vital to meeting project deadlines. For instance, if a project has a gas line install that must be completed before the electrician can start, and the wiring must be done before the plumbing, small delays can push tasks further down the project and potentially push the end date of the project out.
A Gantt chart is helpful at many stages of a project, not just the beginning:
- Tracking project schedules
- How far individual tasks have progressed
- Which resources are being used by which task (i.e. if there is one scissor lift on site and the electrician is using it when the air conditioning engineer needs to use it)
- Can help to identify days of float and rapidly evaporating timeframes
Best practices for Gantt charts
To make a Gantt chart work for a project or organization, follow best practices:
- Enter tasks in groups: This makes it easy for readers to understand what they are looking at.
- Break down tasks into granular components: Gantt charts work best when tasks are detailed.
- Identify responsible teams: Allocating one task per team or company keeps people accountable and also allows for better resource planning.
- Enter accurate start and end dates: This is vital for good planning. If you’re not sure of exact dates, make your best guess.
- Include holidays and time off: You want the project to be as accurate as possible, so including public and planned holidays is vital. When in doubt, plan for extra time, as it allows for float time. Always check staff availability.
- Note down dependencies: Absolutely require one task to be complete before the next can start.
- Use notes: Write down all possible relevant information. If the project manager is not there one day, anyone else should be able to pick up the project and understand what is happening.
Alternatives to a Gantt chart
Critical path network diagrams
Critical Path Network Diagrams are visually superior to Gantt charts because they are simple and clearly show task relationships without clutter. However, they are not as intuitive as Gantt charts.
The diagram is a visual of the whole project, with the longest path between tasks being the overall timeframe or “critical path.” It uses arrows and shapes to create tasks and the pathways between paths.
Project management timeline
Imagine a single bar showing a chronological sequence of events. No complicated details, no extra information. A project management timeline simply shows the high level view of an overall project for stakeholders without the finer details.
While these are excellent for an overview, they cannot replace a Gantt chart.
Kanban board or scrum board
Using a system of cards that can be moved around makes Kanban or Scrum boards ultra flexible. It is easy for colleagues to see where tasks are at—making communicating simple. These can be physical or virtual boards and can be created together as a team to manage sprints. They are easy to modify, adjust, and understand. These boards are essentially a sticky note placed into a column.
A scrum board is similar to a Kanban board as sprints are arranged chronologically. There are vertical and horizontal lanes, designed to track tasks from each sprint. Typically, the lanes include To Do, In Progress, Testing, and Done. While appropriate for software development, a Kanban board may not be acceptable for any other type of project.
A Program Evaluation Review Technique (PERT) chart uses a series of boxes and arrows to create a project layout. It includes subtasks, dependencies, milestones, critical paths, and scheduling details. Rather than a bar chart, it looks like a series of tables linked together with arrows to form a cross-functional flowchart.
Advantages of Gantt charts
Clearly presents information
The layout and design of a Gantt chart makes it easy to see what is happening at a glance. Tasks, sub-tasks, milestones, and projects are all easy to see. You can also see team members allocated to the tasks, project status, percentage of the project completed, and pending work.
Once the chart has been created and distributed, the team should easily see their tasks, the timeframes affecting them, and the overall project status.
Better resource allocation
If several tasks require the same piece of equipment or the same team to complete them, a Gantt chart clearly shows where and when that’s possible. It is simple to see when teams or equipment are over-committed—allowing the project manager to take action to avoid delays.
Team members can see when they are required for a task and can plan their workload accordingly. If the chart is shared easily across an organization, all parties know where the project is at and where it is going.
Complex information management
While a list of tasks or alternative project management charts may work for smaller projects, a Gantt chart is the only one that is complex enough for large, complicated projects.
Disadvantages to Gantt charts
Can be tricky to understand
Gantt charts can become complicated once everything is added in and color-coded. Resources, dependencies, deadlines, lag times, and milestones all take what was a perfectly readable chart and turn it into something that needs to be studied to be understood.
Gantt charts lack flexibility. If a project operates under an agile framework, then Gantt charts become too cumbersome. Each day requires re-planning and rescheduling to reflect the flexible nature of the project.
Time consuming to update
It is a lot of work to update a project. As a result, some changes can be missed, making the chart outdated and hindering effective communication. In the past, Gantt charts were done by hand on paper, requiring a full redraw of the project every time something changed. A rain delay? A re-write. A problem sourcing materials? Another delay, another redraw.
However, with the advent of project management software, this effort is considerably reduced and many programs can automatically adjust as needed.
Many project management software options make it difficult or almost impossible to have a collaborative effort. Gantt charts are also difficult to print and share.
When should you use a Gantt chart?
If your project is complex and spread across numerous teams or geographic locations, then a Gantt chart is the only option. While smaller projects or software developments can be managed with a Kanban or Scrum board, they are not complex enough.
If the organization has great software, this can eradicate most challenges inherent with Gantt charts. Teams can change filters and visibility to help with scheduling and planning. A well-managed Gantt chart allows for accountability, transparency, and ease of management. They should ensure best resource allocation and include time saving and increased productivity measures. Finally, Gantt charts allow for data-driven decisions and timely completion of projects.
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