Gantt chart: explanation, example and step-by-step

Anyone planning a project will sooner or later come across a Gantt chart: a bar chart in which tasks are shown as horizontal bars along a timeline. It is one of the oldest and most widely used planning tools in project management, and at the same time a tool surrounded by misunderstanding — certainly since agile working became commonplace. This page explains what a Gantt chart is, how to build one, when it fits and when it does not, and how to keep it up to date during a project.

What is a Gantt chart?

A Gantt chart is a visual representation of a project schedule in which each task is shown as a horizontal bar. The length of the bar represents the duration of the task, and its position on the timeline shows the start and end date. By stacking all tasks, you get an immediate overview of what happens when, which tasks depend on each other, and which tasks run in parallel.

Origin of the Gantt chart

The name Gantt chart refers to Henry Gantt, an American mechanical engineer and management consultant who popularised the bar chart in the early twentieth century, among other things on large industrial projects. Less well known, but historically just as relevant, is the work of the Polish engineer Karol Adamiecki, who developed a similar planning tool around the same period under the name harmonogram. Both developments arose independently of one another, but it is Gantt's name that has stuck.

What does a Gantt chart consist of?

A complete Gantt chart usually contains the following elements:

• Tasks: the individual pieces of work within the project, usually listed on the left.
• Duration: how long each task takes, shown as the length of the bar.
• Start date and end date: the position of the bar on the timeline.
• Dependencies: arrows or lines showing which task can only start once another task has been completed.
• Milestones: important moments without their own duration, often shown as a diamond on the timeline.
• Critical path: the sequence of tasks that directly determines the minimum duration of the project; a delay on the critical path delays the entire project.
• Resources: who or what is responsible for carrying out a task.
• Progress: often shown as a filled section within the bar, indicating what percentage of a task has already been completed.
• Baseline: the originally planned timeline, used to compare against the current schedule and make slippage visible.

Building a Gantt chart step by step

1. Define the goal and scope of the project. What exactly needs to be delivered, and what explicitly does not?
2. Create a work breakdown structure (WBS). Break the project down into main components and then into concrete tasks.
3. Estimate the duration per task. Base this on experience, comparable projects or input from those carrying out the work.
4. Determine dependencies. Which tasks can run in parallel, and which must wait for another task?
5. Assign resources and owners. Each task ideally has one clear owner.
6. Set out milestones. Mark important delivery points or decision moments.
7. Determine the critical path. This tells you which tasks cannot be delayed at all without affecting the end date.
8. Build the Gantt chart in a tool and share it with the team and stakeholders.
9. Set a baseline once the schedule is approved, so deviations can be measured later.

Example: a website project as a Gantt chart

To illustrate, a simplified schedule for building a new website.

Task	Duration	Depends on
Intake and strategy	1 week	—
Wireframes and content structure	1 week	Intake and strategy
Visual design	2 weeks	Wireframes and content structure
Copywriting	2 weeks	Wireframes and content structure
Technical build	3 weeks	Visual design
Content input	1 week	Technical build, Copywriting
Testing and QA	1 week	Content input
Go-live	1 day	Testing and QA

As an ASCII bar chart, this schedule looks as follows, with each # representing a week:

Week:                        1    2    3    4    5    6    7    8    9
Intake and strategy          ####
Wireframes/content structure      ####
Visual design                          ########
Copywriting                            ########
Technical build                                  ############
Content input                                                 ####
Testing and QA                                                     ####
Go-live (milestone)                                                      ^

It is clear that copywriting and visual design run in parallel, while the technical build only starts once the design is finished. That makes the technical build part of the critical path in this example: a delay there directly pushes back the go-live date.

Advantages and disadvantages of a Gantt chart

Advantages

• Provides an overview of schedule, duration and dependencies at a glance.
• Makes the critical path, and therefore the risks to the end date, visible.
• Works well as a communication tool towards clients and stakeholders who are not involved in the project on a daily basis.
• Supports resource planning: who is needed when.

Disadvantages

• Quickly becomes cluttered on complex projects with many tasks and dependencies.
• Suggests a degree of certainty about duration and sequence that often does not exist in practice, especially for creative or exploratory work.
• Requires maintenance: a Gantt chart that is not kept up to date becomes misleading within weeks.
• Fits less well with work whose scope changes as it progresses.

In short: a Gantt chart is strong at making a schedule visible, but weak at handling uncertainty and change.

When does a Gantt chart fit, and when does it not?

A Gantt chart fits well with projects that have a clear beginning and end, a relatively stable scope, and tasks that can be reasonably estimated in advance — think of construction projects, events, implementations and classic waterfall projects. In that context, the Gantt chart provides a clear grip on sequence, duration and deadlines.

For agile or scrum-driven work, where scope can shift per sprint and priorities regularly change, a Gantt chart fits less well. A fixed timeline with fixed dependencies sits at odds with the principle of short, iterative cycles. In agile environments, kanban boards and product roadmaps are often a better alternative: they show status and direction without locking in a detailed end date per task.

Gantt charts in agile environments

Still, Gantt charts and agile working do not entirely exclude each other. At programme level, where multiple teams and sprints come together, a Gantt chart is sometimes used to show release milestones and dependencies between teams at a high level, while execution within each team still takes place on its own kanban or scrum board. The Gantt chart then acts as an overarching overview, not as a tool for steering daily execution.

Tools for building a Gantt chart

A Gantt chart can be built with a wide range of tools, from simple to extensive:

• Microsoft Project
• Asana
• Monday
• ClickUp
• Jira, usually with an additional plug-in for a Gantt view
• Smartsheet
• TeamGantt
• Excel or Google Sheets, for simple schedules without dedicated software

The choice depends on project size, budget, and whether the team already uses one of these tools for other purposes.

Managing the schedule during the project

A Gantt chart is never finished once delivered; it requires active management for as long as the project runs.

• Update progress regularly, so the team and client retain an up-to-date picture.
• Watch for scope creep: every added task can affect the schedule and the critical path, and deserves a deliberate decision rather than silent addition.
• Build in buffers around tasks with a lot of uncertainty, so small delays do not immediately threaten the end date.
• Compare against the baseline to see if and where the project is slipping, and communicate deviations in good time.

For building a website, a Gantt chart is often part of a broader web design process. For anyone who wants to know exactly what such a project looks like when building a new website, that is where you find the steps behind such a schedule.

Frequently asked questions

What is the difference between a Gantt chart and a roadmap?

A Gantt chart shows detailed tasks, durations and dependencies within a project. A roadmap shows direction and key milestones at a higher level over a longer period, without detailed task-level planning.

Is a Gantt chart suitable for agile projects?

To a limited extent. Within a single scrum team, a kanban or scrum board fits the iterative approach better. At programme level, to show dependencies between teams or releases, a Gantt chart is sometimes still used.

What is the critical path in a Gantt chart?

The critical path is the sequence of tasks that directly determines the minimum duration of the project. A delay on a task within the critical path automatically delays the end date of the entire project.

Which tool should I use for a Gantt chart?

That depends on project size and budget. For simple schedules, Excel or Google Sheets is enough; for larger projects with multiple teams, tools like Microsoft Project, Asana, Monday, ClickUp or TeamGantt are more suitable.

How often should I update a Gantt chart?

Preferably weekly, or more often for projects with frequent changes. A Gantt chart that is not kept up to date gives a distorted picture of actual progress within a few weeks.