Productivity
How to Create a Gantt Chart: Project Timeline Guide
6 min read · Updated 2025
A Gantt chart is one of the most widely used project management tools in the world. Named after Henry Gantt who popularised it in the 1910s, it transforms a project's task list into a clear, visual timeline — instantly showing what needs to happen, when, and in what order.
What a Gantt Chart Shows
- Task list — all project activities in the left column
- Timeline — dates across the top (days, weeks, or months depending on project length)
- Task bars — horizontal bars spanning each task's duration
- Milestones — diamond markers for key deadlines (e.g., approval, launch, handoff)
- Dependencies — arrows showing which tasks must finish before others can start
- Progress — partial fill of task bars showing completion percentage
Step-by-Step: Building a Gantt Chart
- List all tasks — break the project into discrete, manageable activities. Aim for tasks that take 1–5 days; any longer and they are too vague to track.
- Estimate durations — for each task, estimate how many working days it requires. Use historical data from similar projects when available.
-
Map dependencies — identify which tasks depend on others. Common types:
- Finish-to-Start (FS): Task B can't start until Task A finishes (most common)
- Start-to-Start (SS): Task B can't start until Task A starts
- Finish-to-Finish (FF): Task B can't finish until Task A finishes
- Set the start date — working backwards from deadlines or forward from today, place each task on the timeline based on its dependencies.
- Identify the critical path — the longest chain of dependent tasks. This determines your minimum project duration. Any delay here delays everything.
- Assign resources — add who is responsible for each task to enable workload balancing.
Example: Website Redesign Project
| Task | Duration | Depends On | Assigned To |
|---|---|---|---|
| Requirements gathering | 3 days | — | PM |
| Design wireframes | 5 days | Requirements gathering | Designer |
| Client approval | 2 days | Design wireframes | PM |
| Frontend development | 10 days | Client approval | Dev Team |
| Content creation | 7 days | Client approval | Content Writer |
| Integration & testing | 4 days | Frontend + Content | Dev Team |
| Launch | 1 day | Integration & testing | PM |
In this example, the critical path is: Requirements → Wireframes → Approval → Frontend → Integration → Launch = 25 days. Content creation (7 days) runs in parallel with Frontend and is not on the critical path.
Common Mistakes to Avoid
- Ignoring dependencies: Parallel tasks that actually need sequential order cause cascading delays.
- No buffer time: Add 10–20% contingency to any project. Tasks almost always take longer than estimated.
- Never updating the chart: A Gantt chart only has value if it is updated as the project progresses.
- Too much granularity: Tasks shorter than half a day make the chart unmanageable. Group micro-tasks.
Create visual project timelines with BrainBoost's Gantt Chart Tool. Also try the Kanban Board, Timeline Creator, and Mind Map Creator.
Frequently Asked Questions
A Gantt chart is a horizontal bar chart used in project management to visualise a project schedule. Each task is a bar spanning its start and end dates, making it easy to see task durations and the overall timeline.
Task list, timeline, task bars, milestones, dependencies, and progress indicators.
The critical path is the longest sequence of dependent tasks that determines the minimum project duration. Any delay in a critical path task directly delays the entire project.