Projects
A Gantt chart that draws itself from your dates
A Gantt chart does one thing no task list can: it turns time into a picture. One bar per task, stretched across the weeks it runs, and suddenly you can see what a spreadsheet of dates only tells you row by row - what overlaps, what waits, where the crunch weeks are. It is the most-loved planning artefact in project work, and also the most abandoned, for one reason. Most people build it by shading cells with a fill colour.
Shade a bar by hand and you have signed up to re-shade it forever. A date moves - and dates always move - so you clear the old cells, count the new weeks, and colour them in again. Do that across thirty tasks a few times and the chart quietly stops matching reality. The fix is to stop drawing the bar and start generating it.
The bar is a calculation, not a drawing
Everything a Gantt bar shows is already implied by three numbers you hold anyway: a start date, an end date, and a per cent complete. A cell in the timeline grid should shade itself by asking one question - does this week fall between this task's start and end? If yes, it is part of the bar. That is a rule conditional formatting can apply to the whole grid at once.
Do it that way and the magic is simply this: change a date, press Enter, and the bar redraws where it belongs. Nothing to clear, nothing to re-count. The chart cannot fall out of sync with the schedule because the chart is the schedule, rendered.
Reading a Gantt properly
A live Gantt earns its place because of what the eye picks up instantly:
- Overlap. Two long bars running side by side across the same weeks is a resource question waiting to happen - the same people, promised to both.
- Gaps and waits. A bar that starts well after the one it depends on ends tells you there is slack; one that starts the very next day tells you there is none.
- The back half. Bars bunched into the final weeks are the classic shape of a plan that has quietly deferred its risk to the end.
- Progress against position. Overlay a darker segment for the portion already complete, and you can see at a glance whether a task is as far along as its place in the calendar says it should be.
That progress overlay is worth the effort. A bar that is 20 per cent filled but three-quarters of the way through its weeks is telling you something the raw per cent never quite does on its own.
Keeping it live
Two small features turn a static picture into a working instrument:
- A current-week marker. A line or highlight that tracks down today's column, so "where are we?" needs no counting. Every bar to its left should be done or nearly so; every bar it cuts through is live work.
- Rolling week headers. Set the first week's date once and let every later column follow from it. Shift the start and the entire timeline shifts with it - no manual re-typing of thirty date headers when the project slips a fortnight.
If updating your Gantt means anything more than changing a date, it will be out of date within a month - because keeping it current will always lose to the next urgent thing.
A Gantt is not a status report and it is not a to-do list; it is the shape of your plan in time, and its whole value is that a glance replaces a read. Build it so the bars paint themselves, and you get to keep that value for the life of the project instead of the first fortnight.
A Gantt that paints itself
Enter a start, an end and a per cent complete - the brass bar draws itself across the weeks, a darker segment overlays progress, a marker tracks the current week, and rolling headers shift the whole timeline when the plan moves. The bars are conditional formatting, so nothing is ever shaded by hand.