Work Breakdown Structure Example: From WBS to Gantt Chart

By Dr. Ahmed Mortuza Saleque · Updated November 11, 2026 · How we check our content

The short answer

A work breakdown structure (WBS) splits a project into deliverables and smaller pieces of work until each piece can be estimated and assigned. Number them like 1, 1.1, 1.1.1. The WBS says what must be done; a Gantt chart then says when. In practice, the top WBS level becomes your phases or work packages and the lowest level becomes the bars on the Gantt chart.

Open the Gantt Chart Maker →

Tree diagram of a work breakdown structure for a research project with four branches and numbered work packages, next to the matching Gantt chart rows — Tap the image to enlarge it. Free to share with a link to this page.

Example WBS: a two-year field study

Code	Work package or task	Output
1	Project management	Plan, reports
1.1	Kick-off and project plan	Project plan
1.2	Progress reports	Reports every 6 months
2	Study design	Approved protocol
2.1	Literature review	Review chapter
2.2	Protocol and ethics application	Ethics approval
3	Data collection	Clean dataset
3.1	Site recruitment	Signed site agreements
3.2	Field measurements	Raw data
4	Analysis and dissemination	Papers, final report
4.1	Statistical analysis	Results tables
4.2	Papers and final report	Two papers, report

Rules for a good WBS

The 100% rule: the children of each item add up to all of its work, and nothing outside the project appears.
Name items as nouns or outcomes (Ethics approval), not vague verbs (Do ethics).
Stop splitting when a piece can be estimated and owned by one person. A common guide is 8 to 80 hours of effort per lowest-level item.
Three levels are enough for most proposals and small projects.
Include project management as its own branch; it takes real time.

To size each lowest-level item, the man-hours calculator converts people and days into effort, and the business budget calculator helps total the cost.

From WBS to Gantt chart

Give each lowest-level item a duration and a start that respects what it depends on.
In the Gantt Chart Maker, type each top-level item as a group line with no time: 3 Data collection.
Type the tasks under it with their times: 3.1 Site recruitment | Co-I | M4-M7.
Add the outputs from the WBS as Deliverable: lines at their due dates.
Link tasks that wait on others, then check the chart against the WBS: every lowest-level item should have a bar.

WBS vs Gantt chart

	WBS	Gantt chart
Answers	What work is there?	When does it happen?
Shape	Tree or outline	Bars on a calendar
Time shown	No	Yes
Made	First	Second, from the WBS

Common questions

What is the 100% rule in a WBS?

The work in the children of any item must add up to exactly the work of that item, so nothing is missed and nothing extra is included.

How many levels should a WBS have?

Usually three: project, work packages and tasks. Large engineering programmes go deeper.

Is a WBS the same as a Gantt chart?

No. A WBS lists the work without dates; a Gantt chart schedules that work over time.

Can I make a WBS in Excel?

Yes, as an indented list with codes. Paste the same rows into the Gantt Chart Maker, add times, and you have the schedule.