# Gantt chart

Gantt charts get a bad reputation from being used as commitments rather than as plans. Used as a plan, they are good at one specific thing: showing which tasks cannot start until another finishes.

Mermaid has a Gantt syntax, so the chart lives in the page and changes in seconds.

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## When to reach for one

* Project plans with real dependencies rather than a wish list.
* Migration and cutover planning, where sequence is everything.
* Communicating a schedule to people who will not open a project tool.

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## How to draw it in Capable

| **Route** | **Use when**                                   |
| --------- | ---------------------------------------------- |
| Mermaid   | Text, so updating a date is a one-line change. |
| draw.io   | Presentation versions with custom styling.     |

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## A worked example

A migration plan with dependencies and a milestone:

![Gantt chart](https://help.gocapable.com/images/att1417576498.svg)

The source, which you can paste into a new diagram and edit:

```
gantt
  title Platform migration
  dateFormat YYYY-MM-DD
  axisFormat %d %b

  section Preparation
  Inventory current system :done, inv, 2026-09-01, 10d
  Agree target architecture :active, arch, after inv, 7d

  section Build
  Provision environment :prov, after arch, 5d
  Migrate data :crit, data, after prov, 14d
  Parallel run :par, after data, 10d

  section Cutover
  Freeze and switch :milestone, cut, after par, 0d
  Decommission old system :dec, after cut, 5d
```

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## A few things that catch people out

* Dependencies are the reason to draw one. A Gantt chart with no dependencies is a list with bars.
* Mark the critical path; without it every bar looks equally important.
* Keep it coarse. A Gantt chart with sixty rows is a project plan nobody reads.

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## Related

[TimelineHistory, launches and incident reviews.](https://staging.dev.capable-sites.com/wiki/pages/1410138271)

[PERT and critical pathSlack, and the path that has none.](https://help.gocapable.com/diagrams/pert-and-critical-path.html)

[ExamplesWorking diagrams you can copy.](https://help.gocapable.com/diagrams/examples.html)

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_A plan you can change is a plan people trust._