Step-by-step guide
How to make a Gantt chart with ChatGPT
Ask ChatGPT for a project schedule as Mermaid code or a task table. This guide shows how to turn each output into a Gantt chart, check the dates, and make changes.
We use the same six-week bakery-website plan as our worked examples, our Excel guide, and our Notion guide, so you can line them all up side by side.
before you start
Choose an output format
The first method requests Mermaid code, which you can edit and render in a diagram tool. Here is an example with a plain-English task list and the resulting code:
Make me a Gantt chart for launching a small bakery's website in six weeks: design, build, copy, photos, then QA. Give it to me as Mermaid gantt code.
Here's a Gantt chart in Mermaid. Paste it into any Mermaid renderer to see it:
gantt
title Bakery website — launch in 6 weeks
dateFormat YYYY-MM-DD
axisFormat %b %d
section Site
Design :des, 2026-04-01, 14d
Build :bld, 2026-04-08, 18d
Copy :cpy, 2026-04-18, 7d
Photos :pho, 2026-04-22, 10d
QA & fixes :qa, 2026-05-02, 11d
Launch :milestone, lnch, 2026-05-12, 0dCopy this code into a Mermaid renderer to see the schedule as a chart.
method 01 — Mermaid code
The Mermaid route, in four steps
Mermaid is a little text-to-diagram language, and it has a native
gantt
type. This is the route worth knowing, because it ends in a real
Gantt chart
— bars on a date axis — rather than a screenshot or a table.
-
Ask for Mermaid gantt code, not "a chart"
In ChatGPT or another chat assistant, describe the project and request a specific format: "Give it to me as Mermaid gantt code." Include the phases, any fixed dates, and the dependencies you already know.
-
Copy the fenced code block
Copy the code block starting with `gantt`. It contains task names, start dates, durations, and a milestone in Mermaid syntax.
-
Paste it somewhere that renders Mermaid
Paste the block into mermaid.live to preview it. You can also use a Mermaid code block in a supported editor such as Notion, GitHub, Obsidian, or GitLab.
-
Check every date against reality
Check the suggested durations and start dates against the work you expect to do. Fix any conflicts and confirm that each task starts after its prerequisites are complete.
This is what the code above becomes once a renderer draws it — the same five tasks and the launch milestone. To change this schedule, edit the dates or durations in the code and render it again.
method 02 — when you'd rather use a spreadsheet
The task-table route
If the chart is headed for Excel or Sheets anyway, skip Mermaid and ask for the data instead: "give me a table with task, start date, end date, duration and what each task depends on." You'll get something clean enough to paste straight into a spreadsheet and run the stacked-bar trick on.
| Task | Start | End | Days | Depends on |
|---|---|---|---|---|
| Design | Apr 1 | Apr 14 | 14 | — |
| Build | Apr 8 | Apr 25 | 18 | Design |
| Copy | Apr 18 | Apr 24 | 7 | Build |
| Photos | Apr 22 | May 1 | 10 | Copy |
| QA & fixes | May 2 | May 12 | 11 | Photos |
From here you're in spreadsheet territory: our Excel and Google Sheets guides walk through turning exactly this kind of table into bars. Handy — but notice the "Depends on" column is just a note. The spreadsheet won't read it, so nothing reflows when a dependency slips. That's true whether a human typed the table or an AI did.
Limitations
Check the generated schedule
A generated task list gives you a starting point. Before relying on the schedule, check the dates and decide how you will update and share it:
- The example uses fixed dates. The code and table shown here use explicit dates. Check dependent tasks whenever you change the timeline to avoid introducing overlaps or gaps.
- Review the estimates. Suggested dates may vary between answers or conflict with the task order. Compare them with your own estimates and check the dependencies.
- Verify the critical path. If the answer identifies a critical path, verify it by adding up the durations along the dependent tasks.
- Choose how to share it. Use your renderer or spreadsheet to export or share the chart. Check the permissions so recipients can view it.
Mermaid is useful if you want to maintain the chart as text; a task table fits a spreadsheet workflow. For other ways to create and update a chart, our head guide compares every route side by side.
Common questions
AI Gantt charts, answered
Can ChatGPT make a Gantt chart?
You can ask ChatGPT for Mermaid Gantt code or a task table. This guide shows how to render the code as a chart or use the table in a spreadsheet. The workflow you choose determines how you edit and share the result.
What's the best prompt for a Gantt chart in ChatGPT?
Describe the project, list its phases, and specify the output format. For example: "Launch a bakery website in six weeks, with design, build, copy, photos, and QA. Give it to me as Mermaid gantt code." Include any fixed dates and known dependencies, then check the generated schedule.
Can ChatGPT create an editable Gantt chart?
The examples on this page use explicit dates. To change the schedule, edit the Mermaid code or update the spreadsheet data and check the affected tasks. Do not assume that the generated output includes automatic rescheduling.
Does ChatGPT get the project dates right?
Treat generated durations and dates as estimates to review. Check whether the task order, dependencies, and available time fit the project. If the answer identifies a critical path, verify it against the durations and dependencies.
Is there an AI that just makes the Gantt chart for me?
ganttchart.ai accepts a plain-English project description and generates an editable Gantt chart with dependencies and milestones. You can adjust the chart and share it as a link without moving code into a separate renderer.
New to the vocabulary? Every planning term on this page is defined in the plain-English glossary.
AI that draws the chart
Same plain-English input as a ChatGPT prompt — but instead of code to copy and render yourself, you get a finished, shareable, editable Gantt chart in seconds, dependencies and milestones already wired. And when a date slips, it reflows on its own.