Glossary
What is a Gantt chart?
Gantt chart: A Gantt chart is a bar chart that plots a project's tasks against a time axis: each task is a horizontal bar whose start, length and end show when it runs, and milestones appear as markers.
A Gantt chart is a bar chart that plots a project's tasks against a time axis. Each task is a horizontal bar: where it starts, how long it runs and where it ends show when the work happens. Milestones, such as a decision or a go-live, appear as markers on their dates. The chart is named after Henry Gantt, an American engineer and management consultant who developed and popularized it in the 1910s.
Example
The slide below shows a twelve-week engagement as three phases on a month axis, with two milestones drawn as diamonds on rows of their own. Phases that overlap run in parallel.
Parts of a Gantt chart
| Part | What it shows |
|---|---|
| Rows | One task, phase or workstream each |
| Time axis | The calendar, in weeks or months, along the top |
| Bars | When a task starts, how long it takes and when it ends |
| Milestones | Points in time without duration: decisions, deliveries, go-lives |
| Dependencies | Arrows that show which task must finish before another can start |
| Today line | A marker for the current date, so progress is visible |
From project plan to slide
A planning tool holds every task, and a slide holds the story. For a slide, simplify:
- Show phases, not tasks. Five to ten rows are readable. Put the full plan in the appendix.
- Pick one time scale and label it. Weeks or months, with real dates or “Week 1 to 12”. Add the start date, because “Week 1” alone is ambiguous.
- Mark the moments that need the audience. Decisions, approvals and handovers become milestones, and the slide says who is asked to act.
- Draw dependencies only where they matter. A few arrows make the critical links visible. Many arrows make a tangle.
- Show where you are. A today line or a status color tells readers what is done, what is running and what is next.
- Title the finding. “Twelve weeks from kick-off to handover” gives the total duration, which is the point of most proposal timelines.
Typical mistakes
- Too many rows. A hundred tasks on one slide cannot be read. Group them and move the detail to the appendix.
- False precision. Bars drawn to the day for an estimate promise more than you can keep. Use weeks or months.
- No milestones. Without decision points, the chart shows busyness, not control.
- Colors without meaning. Use color for the phase or the owner, and say which in a legend.
- A Gantt chart for a vision. Themes without dates belong on a roadmap, not in a schedule.
Related terms
A roadmap shows themes over broad periods, while a Gantt chart shows dated work. The example comes from a consulting proposal, and the same slide fits a project status report, where RAG status shows whether each bar is on course.
FAQ
Frequently asked questions
Who invented the Gantt chart?
It is named after Henry Gantt, an American engineer and management consultant who developed and popularized it in the 1910s.
What is the difference between a Gantt chart and a roadmap?
A Gantt chart shows tasks with exact start and end dates and often their dependencies. A roadmap shows themes or goals over broad periods such as quarters, without detailed dates. Use a Gantt chart to plan delivery and a roadmap to align on direction.
How many tasks should a Gantt chart on a slide have?
About five to ten rows. Show phases and milestones, not every task. Keep the detailed plan in a planning tool and refer to it in the appendix.
What is a milestone in a Gantt chart?
A milestone is a point in time with no duration, such as a decision, a delivery or a go-live. It is usually drawn as a diamond on the date it occurs.
Keep reading
Charts and numbers
- GuideChoosing the right chart
Which chart fits which message: bars to compare, lines for trends, a waterfall for bridges. Includes when a pie works, when a table beats a chart, common traps.
- Free toolSlide contrast checker
Check the WCAG 2.2 contrast ratio of two slide colors. See AA and AAA results for text and charts, a live slide preview and the nearest colors that pass.
- GlossaryWaterfall chart
A waterfall chart shows how a start value becomes an end value through a series of increases and decreases. Definition, how to read it and typical mistakes.
- GlossaryHarvey balls
Harvey balls are round pictograms that show how far a criterion is met, from empty to full in quarter steps. Meaning, symbols and how to use them on slides.
- GlossaryTwo-by-two matrix
A two-by-two matrix sorts items into four quadrants using two criteria. Definition, well-known examples such as the Eisenhower matrix, and how to build one.
- GlossaryDriver tree
A driver tree breaks a metric such as revenue or profit into the measurable drivers behind it, linked by simple math. See a worked example you can copy.
Where to go next
- TemplateProject kickoff
Open a project on 9 slides: goal, scope, success measures, timeline, team, ways of working, risks and the next 30 days. A kickoff template with an example.
- ConvertExcel to PowerPoint
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