Support — Gantt Chart for Sheets

Email: slowgrain.dev@gmail.com — we reply within five working days.

Getting started

  1. Open the spreadsheet containing your task list.
  2. Extensions → Gantt Chart for Sheets → Build Gantt chart.
  3. A tab named Gantt appears with your chart. Your task list is not modified.

Re-run it whenever the plan changes; the chart is rebuilt from scratch each time.

How to lay out your task list

Your table does not have to start at cell A1, and column order does not matter. Headings are recognised automatically:

Column Recognised headings Required?
Task name Task, Name, Title, Activity, Description, 작업, 작업명 Yes
Start date Start, Start Date, Begin, From, 시작, 시작일 Yes*
End date End, End Date, Finish, Due, 종료, 종료일 One of End or Duration
Duration Duration, Days, Length, 기간, 일수 One of End or Duration
Dependencies Predecessors, Dependencies, Depends On, Blocked By, 선행작업 No
Progress % Complete, Progress, Completion, 진행률 No
Outline level Level, Outline Level, Indent, 레벨 No
Owner Owner, Assignee, Resource, Team, 담당자 No
Task ID ID, Task ID, WBS, No No

* A task without a start date is fine if it has a dependency to derive one from, or if it is a summary row with children.

Common questions

A task is missing from the chart. It will be listed below the chart under “Not shown on the chart”, with the reason. Use Extensions → Gantt Chart for Sheets → What can’t be scheduled? to see the full list.

Dates are being read the wrong way round (03/04 read as 4 March, not 3 April). The day/month order is inferred from your sheet. Include at least one unambiguous date — any date with a day above 12, like 25/04/2026 — and the whole sheet will be read that way. Using ISO dates (2026-04-03) removes the ambiguity entirely.

How do I write a dependency? Put the predecessor’s ID in the Predecessors column. 12 means “start after task 12 finishes”. 12+3 adds three days of lag. 12-1 starts a day early. Separate several with commas: 12, 14.

How do I make phases? Add a Level column: 0 for a phase, 1 for its tasks, 2 for sub-tasks. Phase rows need no dates — they span their children automatically. A Parent column with the parent’s ID works too.

Weekends are being counted. Turn on Skip weekends in the menu. To exclude specific holidays as well, contact support — holiday lists are configured per sheet.

“Circular dependency between…” Two or more tasks depend on each other, directly or through a chain. The named tasks are left off the chart. Break the loop and rebuild.

The chart is too wide to read. The timeline picks its own scale from the project length. A very long project is drawn in weeks, months or quarters rather than days. There is no maximum project length.

I have more than 50 tasks. That is the free limit. Pro removes it. Tasks beyond the limit are reported, not silently dropped.

Licence keys

Entering a key: Extensions → Gantt Chart for Sheets → Enter licence key. Removing a key: open the same dialog, clear the box, press OK.

A key applies to your Google account, so it works in every spreadsheet you open — you only enter it once.

Lost your key? Email support with the order reference from your receipt.

Key rejected? Keys begin with GS1. and contain no spaces. Check that the paste did not pick up a trailing space or a line break. A key that fails is never saved, so your previous state is untouched.

Reporting a problem

Email slowgrain.dev@gmail.com with:

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