Project Management guide · Scheduling and time
Gantt Chart: What It Is, How to Make One and Examples
A Gantt chart is a bar chart that shows a project's activities against a timeline. Each activity is a horizontal bar whose position and length show when it starts and how long it takes, with lines or arrows showing dependencies between activities.
Key takeaways
- A Gantt chart shows activities as bars on a timeline with dependencies and milestones.
- Build it from activities, durations and dependencies so dates calculate automatically.
- Highlight the critical path and compare progress with a baseline.
- Summarise large charts for stakeholders.
Parts of a Gantt chart
| Element | What it shows |
|---|---|
| Task list | Activities down the left side, often grouped by phase or WBS level |
| Timeline | Days, weeks or months across the top |
| Bars | Start, finish and duration of each activity |
| Dependencies | Arrows linking predecessors and successors; see task dependencies |
| Milestones | Diamonds marking key events of zero duration; see milestones |
| Progress | Shading inside each bar showing percentage complete |
| Today line | A vertical line showing the current date |
| Critical path | Bars highlighted where any delay delays the project; see critical path |
How to make a Gantt chart
- List the activities from your work breakdown structure.
- Estimate the duration of each activity.
- Record the predecessors for each activity and the dependency type (usually finish-to-start).
- Enter the activities into a scheduling tool or spreadsheet and set the project start date.
- Let the tool calculate the dates from the dependencies rather than typing dates manually.
- Add milestones, owners and resource assignments.
- Review the critical path and float, then baseline the chart.
- Update progress at least weekly and compare it with the baseline.
Worked example
Using a project start of Monday and five-day working weeks, an office move might look like this:
| Activity | Duration | Predecessor | Starts | Finishes |
|---|---|---|---|---|
| A Plan move | 3 days | - | Day 1 | Day 3 |
| B Order furniture | 4 days | A | Day 4 | Day 7 |
| C Book removals | 2 days | A | Day 4 | Day 5 |
| D Install furniture | 5 days | B | Day 8 | Day 12 |
| E Pack and label | 3 days | C | Day 6 | Day 8 |
| F Move and unpack | 2 days | D, E | Day 13 | Day 14 |
| Milestone: office open | 0 days | F | Day 14 | Day 14 |
On the chart, bars A, B, D and F form the critical path. Bars C and E share 4 days of float: together they can slide up to 4 days to the right without moving the finish date.
Advantages and limitations
| Advantages | Limitations |
|---|---|
| Easy for anyone to read | Large charts become cluttered and hard to read |
| Shows overlaps and sequence at a glance | Does not show effort or cost unless you add them |
| Makes the critical path visible | Can give false precision when work is uncertain |
| Good for tracking progress against a baseline | Needs regular updates to stay useful |
Tips
- Keep the top-level view to 20 to 40 lines for stakeholders and collapse the detail.
- Use dependencies, not fixed dates, so the chart reschedules itself.
- Show the baseline bars alongside current bars to make slippage obvious.
- Pair the chart with a project timeline for executive audiences.
Free templates for this topic
Frequently asked questions
What is a Gantt chart used for?
Planning, communicating and tracking a project schedule: who does what, when, and in what order.
Who invented the Gantt chart?
It is named after Henry Gantt, who popularised this style of chart in the early twentieth century.
What is the difference between a Gantt chart and a timeline?
A timeline shows key events and phases simply; a Gantt chart shows every activity with durations and dependencies.
Can I make a Gantt chart in Excel?
Yes, with a stacked bar chart or a template, but spreadsheets do not calculate dependencies or the critical path. Dedicated Gantt chart software does.
What does a diamond mean on a Gantt chart?
A milestone: a significant point in time with zero duration, such as an approval or a go-live.
What do arrows on a Gantt chart mean?
They show dependencies, usually that one activity must finish before the next can start.
Is a Gantt chart Agile or Waterfall?
It is most associated with Waterfall, but Agile teams use simplified versions for release planning; see agile Gantt charts.
How do you show the critical path on a Gantt chart?
Most tools highlight critical activities in red once dependencies and durations are entered.
What is a baseline in a Gantt chart?
A saved copy of the planned dates, shown as thin bars, so you can compare actual progress with the original plan.
Which tools have Gantt charts?
Many tools do, including those reviewed at project management tools, such as Smartsheet and Wrike.