Gantt chart generator

Spreadsheet in, chart out, spreadsheet back

Most project schedules already exist in Excel. The problem is never the data — it is that a table of dates communicates nothing to anyone who was not in the planning meeting. This tool closes that loop: import the file you have, get a chart you can paste into a deck, and export the file back with the schedule as a proper sheet.

The export is the part worth explaining. When you import an XLSX, we keep the original ZIP intact and add a single worksheet to it, patching only the three index files the Open XML format requires — the relationship list, the sheet list and the content-type map. Your formulas, formatting, other tabs and pivot sources come back exactly as they were. That is deliberately different from tools that parse a spreadsheet into memory and write a new one, which quietly discards everything they did not understand.

How the columns are matched

Column order does not matter. The first row is scanned for recognisable headers in English and Portuguese — task/tarefa, start/início, end/fim, progress/progresso, group/grupo — and the columns are mapped from whatever it finds. If no header is recognisable, the first five columns are used in that order, which handles files exported from other planning tools.

Dates are the fragile part of any spreadsheet import, so four formats are accepted: ISO, dd/mm/yyyy, mm/dd/yyyy and Excel's own numeric serial. That last one has a famous trap — Excel's epoch is 30 December 1899 rather than 1 January 1900, because it inherited a bug from Lotus 1-2-3 that treats 1900 as a leap year. Using the intuitive epoch puts every imported date two days off.

Reading the chart

• Bar length is inclusive. A task from the 1st to the 5th is five days, not four. This is what people mean by dates on a schedule, and it is where a lot of hand-built charts are quietly wrong.
• Progress fills from the left. The solid portion is the percentage complete against the faded full bar, so slippage is visible against the today line rather than requiring arithmetic.
• The today line is the point of a Gantt. A bar that ends before it and is not at 100% is late; a bar that is 80% done with 20% of its time left is on track.
• Groups colour themselves. Fill the group column and each phase gets its own colour automatically. Leave it empty and everything uses your chosen colour.

Time scale

Auto picks the granularity that will not crowd the axis: days for a month or less, weeks up to six months, months beyond that. Override it when you are presenting to a specific audience — an engineering team usually wants weeks, an executive review usually wants months, and forcing days on a year-long project produces an unreadable axis.

What this deliberately does not do

There are no dependencies, no critical path and no resource levelling. Those are the features that turn a chart into project-management software, and they need a data model that a spreadsheet cannot carry. If you need them, you need MS Project or a planning tool. This is for the far more common case: you already know the schedule and need a picture of it that other people can read.

Privacy

The spreadsheet is unzipped, parsed, rebuilt and re-zipped entirely in your browser. No upload, no account, no limit.