Gantt chart maker

The chart is named after Henry Gantt, who popularised it around 1910, though Karol Adamiecki had published the same idea in Poland fifteen years earlier under a different name. It was used to plan the Hoover Dam and the American interstate system, on paper, with the bars redrawn by hand every time anything moved — which explains a great deal about why project plans of that era changed so rarely.

Both ends of a task are inclusive here, so a task from the 5th to the 5th is one day rather than zero. That sounds pedantic and is not: a zero-length bar is invisible, and single-day tasks — a launch, a review, a handover — are among the most common things anyone puts on a chart.

What this deliberately does not model is dependencies. A real Gantt chart draws arrows between tasks that cannot start until another finishes, and that is where the value is in serious project management — it is what lets software recalculate everything downstream when one task slips. Adding it means a dependency graph, cycle detection and automatic rescheduling, which is a different product. This draws what you tell it.

So it is right for a plan you want to show someone — a proposal, a status update, a wall — and wrong as a planning tool for anything with real interdependencies. For that you want software that recalculates.

The output is landscape because a timeline needs width far more than height, and vector so it stays sharp printed at A3 for a wall.