A Gantt chart is a time planner which is very useful for planning projects. It is a bar chart showing a graphical picture of timetabling. It’s advantage is it can show how different parts interact with each other (which follow on from others, and which can work at the same time).
When to use
They come in use when organizing timing and resources for projects. They let you know what activities rely on others, and where you’re concentrating your resources at any one time. They are often the best tool to find the expected length of a project, and see which activities are the highest risk for holding it up.
- Draw a chart split by time (usually by weeks) across the top (x axis) with activities down the side (y axis)
- Identify the different activities (tasks) which need to be achieved during the project
- Calculate the length of time of each project
- Calculate what tasks must wait for another to finish before they can start
- Arrange each activity in the bar chart with a bar the length of the activity
- (Optional) mark on the graph where an activity relies on another being completed using arrows
- You should now have a chart showing a good high level overview of your activities:
In the example, the project begins with activity A, closely followed by activity B, and the two can operate at the same time. Activity E then can’t start until activity C has ended. These are useful for all sorts of planning – my friend uses them to make sure all the parts of his Christmas dinner are ready at the right time!
It’s clear from this example that although the project is expected to finish after 10 weeks, if activity A took 4 weeks, you would already be expecting to finish the project late, even though you’re less than half way through, so it can give some advanced warning of issues.
It’s a very top level diagram, so the details of the activities will have to be kept elsewhere. It’s also limited in showing any complicated interdependencies, e.g. it’s unclear in the above what effect activity B taking 3 weeks longer would have, but it’s a key tool in getting an overview of your project, and keeping the process on target.