Gantt Charts

Gantt charts are the most widely used tool for visualising project schedules. They show tasks as horizontal bars along a timeline, making it easy to see what needs to happen, when, and how tasks relate to each other.

What is a Gantt Chart?

Named after Henry Gantt who popularised them in the 1910s, Gantt charts are used for:

• Visualising the schedule - See the entire project at a glance
• Communicating plans - Easy to understand for all stakeholders
• Tracking progress - Show actual vs planned progress
• Identifying issues - Spot delays and overlaps quickly

Gantt Chart Anatomy

Basic Elements

Components Explained

Creating a Gantt Chart

Step-by-Step Process

1. List All Tasks

Start with your WBS work packages:

• Break down to manageable activities
• Include project management tasks
• Don’t forget testing, reviews, approvals

2. Estimate Durations

For each task, determine:

• How long will it take?
• Working days or calendar days?
• Any constraints (deadlines, dependencies)?

3. Sequence Tasks

Arrange tasks in logical order:

• What must happen first?
• What can run in parallel?
• What are the dependencies?

4. Add Dependencies

Link related tasks:

• Predecessor relationships
• Lead and lag time if needed
• External dependencies

5. Assign Resources

Add resource information:

• Who is responsible?
• How much effort?
• Any resource conflicts?

6. Set Baseline

Save the original plan:

• Baseline for comparison
• Track variance later
• Don’t change without change control

Showing Dependencies

Dependencies show the relationships between tasks.

Dependency Types on Gantt

Milestones

Milestones mark significant events or deliverables with zero duration.

Common Milestones

Progress Tracking

Showing Progress

Update the Gantt chart to show:

Baseline Comparison

Compare current schedule to baseline:

Baseline:  [===========]
Current:   [===============]  ← 4 days behind

Resource Assignment

Adding Resources to Gantt

Resource Levelling

When resources are over-allocated:

1. Identify conflicts - Same person on parallel tasks
2. Prioritise - Which task is more critical?
3. Adjust schedule - Delay lower priority tasks
4. Split tasks - If possible, work in phases
5. Add resources - If budget allows

Gantt Chart Best Practices

Do

Don’t

Gantt Chart Levels

Different audiences need different levels of detail:

Executive Summary Gantt

Common Gantt Chart Mistakes

1. No Dependencies Shown

Problem: Tasks appear independent when they’re not Solution: Always show task relationships

2. Summary Tasks Only

Problem: Can’t track detailed progress Solution: Break down to trackable work packages

3. Over-Optimistic Durations

Problem: Schedule slips immediately Solution: Use realistic estimates, add contingency

4. Ignoring Resource Capacity

Problem: Impossible schedules Solution: Check resource availability, level workload

5. No Baseline

Problem: Can’t measure variance Solution: Set and protect the baseline schedule

6. Set and Forget

Problem: Chart becomes irrelevant Solution: Update weekly, track actuals

Gantt Chart Tools

Software Options

Gantt Chart Checklist

Before sharing your Gantt chart, verify:

• All tasks from WBS included?
• Durations realistic?
• Dependencies shown?
• Milestones marked?
• Resources assigned?
• Critical path visible?
• Baseline set?
• Time scale appropriate for audience?
• Legend explains colours/symbols?
• Update date shown?

Worked Example

Office Move Project

Key observations:

• Critical path runs through lease → fit-out → move
• IT infrastructure runs in parallel with construction
• Old office handover starts during unpacking
• Clear milestones mark phase completions

Related Resources

• Work Breakdown Structure - Source of tasks for Gantt
• Critical Path Method - Identifying the critical path
• Estimation Techniques - Estimating task durations
• Risk Management - Schedule risk management