What Is a Gantt Chart? How to Read One and When to Use It

You keep hearing the term Gantt chart, but you are not sure how to read one, or whether it is worth using in your own work. This article explains what a Gantt chart is, the elements it is made of, a simple way to read one even if you have never done it before, and the situations where it fits and where it does not, written for readers with no project management background.

What Is a Gantt Chart?

A Gantt chart is a schedule that lists tasks on the vertical axis and time (days, weeks or months) on the horizontal axis, and shows each task as a horizontal bar running from its start date to its end date. It is named after Henry Gantt, an American mechanical engineer and management consultant who devised it in the 1910s. Today most project management tools include it as a standard feature, and it remains the most basic way to represent a schedule.

What a Gantt chart tells you

A single Gantt chart lets you grasp three things.

• Duration: when each task is planned to start and finish
• Sequence and overlap: which work runs in parallel, and which work is waiting for something else to finish
• Progress: as of today, which tasks are on track and which are behind

A task list can hold dates too, but you cannot see overlaps or delays without comparing the dates one by one. The defining strength of a Gantt chart is that it shows these intuitively through the length and position of the bars.

How it differs from a WBS and a Kanban board

Two other methods are often used alongside Gantt charts: the WBS and the Kanban board. Each shows something different.

• WBS: a hierarchical breakdown of what needs to be done, with nothing left out. It has no time axis
• Gantt chart: the broken-down tasks assigned to when they will be done, laid out along a time axis
• Kanban: columns showing what state each item is in now (not started, in progress, done and so on). It manages flow rather than deadlines

The usual order is to identify tasks with a WBS first, then schedule them with a Gantt chart.

The Elements of a Gantt Chart

The look varies somewhat between tools, but a Gantt chart is broadly made up of the following elements.

• Tasks (rows): the list of work on the left, often grouped by phase
• Time axis (columns): the dates across the top, shown by week or month for longer periods