Gantt charts can be daunting. So much information, so many new terms to learn. But they are a key part of the project manager’s toolset and if you want to manage your projects professionally you need to know how they work.
The good news is that once you get over the initial shock of seeing a Gantt chart for the first time, they are really easy to use and understand.
In this article we’ll explain everything you ever wanted to know about Gantt charts (but might have been afraid to ask.) Let’s start with the basics.
What is a Gantt Chart?
First, know that Gantt charts rock. Project management would be a much less organized place without them. Gantt charts are used for projects of all sizes and they are a useful way of showing what work has to be done on what day.
Tell me about Henry Gantt
Oh, you think it was Henry Gantt who first had the idea of project planning on bar charts? Well, that’s not totally true.
Karol Adamiecki devised the first ‘Gantt’ chart, back in 1896. He was a Polish engineer turned management professor who came up with the idea of displaying processes visually so that he could make it easier to see production schedules – he did most of his work in the steel industry. He called it the harmonogram but he published his articles on it in Polish and Russian, so the English-speaking world didn’t know much about it.
Henry Gantt had the same idea, but about 15 years later. In 1910 Gantt started planning visually with bar charts to allow supervisors in the steel works to see if production was on track or behind schedule. It was Gantt’s name that got attached to this way of planning, but today it’s generally recognized that Adamiecki had the idea first.
What Do I See on a Gantt Chart?
There are two main parts to a Gantt chart: a column that lists the project tasks on the right and a chart that shows how long each task takes on the left. Each task has a corresponding bar on the chart that runs horizontally. The bar starts on the date that the work is scheduled to start. The longer the bar, the longer the task will take. Shading on the bar indicates how complete the work is. When the bar is totally shaded, the task is finished.
The other things you’ll see on a Gantt chart are:
Milestones: These are represented by a diamond symbol. A milestone marks the end of a piece of work or phase of the project. They are often fixed dates or important dates that you need to be aware of.
Read more: Find out why diamonds are a project manager’s best friend in this article about using milestones in your scheduling.
Dependencies: These are links between tasks. For example, you can’t test the software until the development is finished, so development and testing are linked. Links are shown with lines on the Gantt chart. The arrow at the end of the line shows which way the dependency goes. In other words, the arrow points to the task that comes next.
Read more: Learn how to manage task dependencies.
Summary tasks: A summary task is an ‘umbrella’ task that is made up of various individual tasks. It is a good way of grouping tasks together, especially as part of a project stage or phase.
You can ‘roll up’ your tasks (in other words, hide them from view) so that only the summary task is on show. This is really helpful when you have hundreds of tasks, as it lets you focus on the important ones for now. For example, you can roll up all the tasks that are completed so you don’t see them.
Today’s date: You can display a vertical line that shows you today’s date at a glance.
From all the information on the Gantt chart you can easily see:
- The start date of the project
- What the project tasks are
- When each tasks starts and finishes
- How long each task will take
- How tasks group together, overlap and link with each other
- The finish date of the project.
And don’t forget that the columns – the right-hand section of the Gantt chart – give you even more information.
What Are the Common Gantt Chart Columns?
The most common Gantt chart columns are:
- Task name: Unsurprisingly, this is a description of the task.
- Planned start date: This is the date that you aim to start working on the task.
- Planned duration: This is a single number that reflects how many days there are between the planned start date and the planned finish date. It’s based on working days, so if a task is planned to take a week it will reflect 5 (working) days.
- Planned effort: How many hours of work the task will take within the duration. Think about painting a wall. It might only take you an hour to paint the first coat but then you’ve got to leave it two hours to dry before the next coat. Then you paint again and leave it to dry again. That’s only two hours of actual painting (effort) but six hours in total (duration).
- Percent complete: A figure, mostly always based on an educated guess by the person doing the task, of how much work they have done and how much is still to do
Pro Tip: Beware of tasks that stay at 80% complete for too long. This is a sign that the task owner doesn’t really know how much work there is still to do. When you ask for updates, the percent complete should move up each time unless no work has genuinely taken place. Monitoring percent complete is a good way to get an early warning about tasks that might run late.
- Resource: This column tells you the name of the person, people, or resource type (e.g. Developer) who has been allocated to work on the task. At the start of the project you may only have resource type but as you go through you should be able to replace this with the names of actual team members.
- Dependencies: You can also show the task dependencies in number form. This is often an easier way of quickly finding out which task links where. Use the numbers in this column to track back the task dependencies – it can be faster than trying to trace a spidery line on the Gantt chart.
- Still not sure about creating links between tasks? Our project management expert, Jennifer Bridges, PMP, explains it all in this video:
These are the most common ones but you can also set your Gantt chart columns to show you virtually anything you want including actual start and finished dates, planned and actual cost and Work Breakdown Structure numbering.
How Does It Know When The Team is Working?
Good question. Planned duration and effort, and the overall start and finish times take working time into account.
The Gantt chart software pulls working time information from the resource working hours that you set. This gives you the option to change the available working time for each team member, which can be handy if you have people who aren’t able to work the standard 8-hour day solely on your project. You can also change working time for everyone, for example if you’re closing the office for a staff event or want to make sure that no one is scheduled to work on a bank holiday.
Can I Link Tasks to Risks and Issues?
Yes, if your project management software allows it (ProjectManager.com does, by the way). You can link tasks to risks, issues and changes which makes it easy to navigate in the software and to highlight when a potential problem might need your attention.
Can I Personalize my Gantt Chart?
Of course. If you don’t want all the default options to show – or if you want even more options on display, navigate to the Gantt chart settings of your project management software and select what you want to see.
One of the easiest and most common things to fiddle with is the division of time that is displayed on the Gantt chart. There are two ‘levels’ of time displayed, normally the week and then the day. You can change the top tier to show weeks, months, quarters or even years and make the lower tier reflect the smaller division of time.
You can also color-code tasks, shade out non-working time and personalize other elements so it looks just right.
Tell Me How To Create A Gantt Chart
In the days before computers, schedulers used to draw out their Gantt charts by hand. This was obviously a lot of work and as soon as something changed they had to do it all again.
Today, I wouldn’t recommend trying to plot your Gantt chart by hand. Use project scheduling software to automatically calculate your Gantt chart. It takes the legwork out of it for you!
And How Do I Use It?
Create your Gantt chart during the project planning phase. It’s the guide that you will use to direct and monitor the project work as the project moves forward.
It is a living document and should be your ‘go to’ guide for what’s happening on the project at any time. Ideally you should update your Gantt chart at least weekly, using the actual timesheet data to show how far through each task is.
As well as reflecting the latest status on planned tasks, you should also update it with changes to resources, and any new or deleted tasks. Your Gantt chart should always show you what has happened and what is still to come so get familiar with your Gantt chart scheduling software: you’ll be using it a lot!
For more tips on how to use a Gantt chart, check out our project management expert Devin Deen in this video.
How do I print a Gantt Chart?
With care! Gantt charts are often difficult to print because they stretch horizontally over several pages. You used to often see project schedules printed and taped together then hung on the wall, but today most teams try to save the paper and work as far as possible online.
Of course, sometimes you’ll need to print out your Gantt chart, or at least a summary of it. Here are 5 tips:
- Print it all on one page if possible. If that makes the text too small to read then…
- …Change the time divisions so you contract the overall timeline (and therefore size) as much as possible. For example, if your display is set to show every day, change it so that the time slots shown are weekly or even monthly. That will make the bar chart part of the Gantt much shorter, so it doesn’t print on so many pages.
- Roll up your tasks, especially if they are already complete.
- Use print preview: it’s annoying to print a lot of pages and then realize you made a mistake! Check it out first.
- Print page numbers if you can, so that you can put the Gantt chart together again if it is on several pages.
Next Steps for Using Gantt Chart
The best way to get comfortable using a Gantt chart is to actually do it. Create a project in your scheduling software and play around with it. Practice using the different settings to see which columns give you the information that you want. Your test project file is also handy if you want to try out a new feature or view before you try it on a ‘real’ project schedule.
The more you use Gantt charts, the easier they will become and the more confident you’ll get at using them.