IB Business Management HLTopic 6 — The Business Management ToolkitPapers 1, 2 & 3HL only~9 min read
Using Gantt Charts
A Gantt chart is a project timetable drawn as bars. Tasks run down the left, time runs across the top, and the length of each bar shows how long that task takes. One glance tells you what is running, what is late and what could be done at the same time.
📘 What you need to know
Tasks go on the vertical axis, time goes on the horizontal axis.
The width of each bar shows how long the task lasts; where it starts shows when it begins.
Bars that overlap in time are tasks that can run at the same time.
Dependencies are tasks that cannot start until another finishes. They are often joined by a line.
Charts can show progress (a percentage complete) and who is responsible for each task.
The finish date of the project is where the last bar ends.
Reading a Gantt chart
Task C cannot start until A finishes, so its bar begins in week 4. That gap is a dependency, and it is what fixes the finish date.
What the chart is telling you
Task
Starts
Lasts
Depends on
A Design the unit
Week 1
3 weeks
Nothing
B Order equipment
Week 1
4 weeks
Nothing
C Fit out the kitchen
Week 4
3 weeks
A
D Recruit staff
Week 5
2 weeks
B
E Train staff
Week 7
2 weeks
C and D
F Opening week
Week 9
1 week
E
Read the chart backwards to find what really controls the finish date. F waits for E, E waits for C, C waits for A. Those four are the chain that decides everything. B and D have slack, so a delay there costs nothing.
Worked examples
WORKED EXAMPLE
Using the chart above, state the total time the project is expected to take, and identify two tasks that can run at the same time. [3 marks]
Step 1: find where the last bar endsTask F ends at the close of week 9.Total project time = 9 weeks [1]Step 2: look for bars sitting side by side in the same weeksA and B both run in weeks 1 to 3 [1]. C and D both run in weeks 5 and 6 [1].9 weeks; A with B, and C with D“same time” always means the bars overlap horizontally
WORKED EXAMPLE
Task C overruns by two weeks. Explain the effect on the opening date. [3 marks]
Step 1: who is waiting on C?E cannot start until C is finished [1].Step 2: follow the chainE is pushed from week 7 to week 9, and F is pushed from week 9 to week 11 [1].Step 3: state the effectThe opening is delayed by the full two weeks, because C has no spare time built into the schedule [1].Opening slips from week 9 to week 11a delay only matters if something is waiting on it
Not every delay costs you. If task D slipped by one week it would still finish before E needed it, so the opening date would not move at all. That spare time is called float, and it is the idea critical path analysis measures properly.
How useful are Gantt charts?
Strength
Weakness
Anyone can read it at a glance, including non-managers
Big projects with dozens of tasks become unreadable
Shows planned progress against actual progress
Redrawing it every time something moves eats management time
Makes it obvious which tasks can run together
Does not show how much labour or money each task needs
Helps schedule staff and deliveries for the right week
Rigid: one change can force the whole chart to be rebuilt
Good for projects with clear, known steps
Weak for projects that keep changing shape as they go
💡 Exam tips
If asked to draw one, get the start weeks right first, then the lengths.
Count carefully. A task lasting three weeks starting in week 1 finishes at the end of week 3, not week 4.
State the total project time as the point where the final bar ends.
For “will it finish on time?”, compare that end point to the deadline in the case study and say yes or no clearly.
Mention that a Gantt chart shows time only, not cost or workload. That is a reliable evaluation point.
Say it should be used alongside other project tools, such as critical path analysis.
⚠ Common mix-ups
Adding all the durations together to get the project length. Overlapping tasks make it shorter than that.
Starting a dependent task too early because there is a gap in the chart.
Reading the bar width as importance. A long bar just means a long task.
Assuming every delay pushes the end date. Only delays on the critical chain do.
Forgetting the chart shows no costs, then using it to argue about budget.
Mixing up axes. Tasks down the side, time across the top.
Up next: Comparing Cultures With Hofstede — projects and plans work differently in different countries. Hofstede gives you a structured way to compare them.
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